One day after the assassination of Rajiv Gandhi, his party elected Gandhi's widow as its leader Wednesday in hopes that she could rally its candidates to victory in parliamentary elections.

The choice of Italian-born Sonia Gandhi came as the dazed nation began a week of mourning for her husband.The former prime minister was killed Tuesday night by a bomb that may have been carried by a suicide assassin who presented him with flowers.

It was not known if Mrs. Gandhi, 43, would accept the offer to lead the party.

An anonymous caller to a national newspaper Wednesday claimed responsibility for the bomb that killed Gandhi on behalf of minority groups in India and Sri Lanka who are seeking their own homelands, an editor said.

The claim was the first received by an Indian newspaper. Police would not dismiss the call, saying they had no idea whether it was a hoax.

Indians were voting for a new Parliament when Gandhi was slain while campaigning. Gandhi's Congress Party had been expected to win but was expected to fall short of a majority needed to avoid forming a coalition government.

After the assassination, government officials postponed further balloting until next month.

Mrs. Gandhi's election to lead the Congress Party appeared to be an appeal for a sympathy vote when the national elections resume.

When Rajiv's mother, Indira, was assassinated in 1984 by Sikh bodyguards, the party turned to her son to rally the party and it went on to win by a landslide.

If the party goes on to win this time, the politically inexperienced Mrs. Gandhi would be in a position to become prime minister and perpetuate the family dynasty that has ruled India for 37 of its 43 years as an independent nation. But the party would not be required to make her prime minister.

Gandhi, 46, was killed minutes after he arrived at a rally in southeastern Tamil Nadu state. Fifteen other people also died in the blast. First reports from witnesses said the bomb appeared to have been concealed in a basket of flowers sitting on the ground.

The news agency Press Trust of India reported Wednesday that police believe Gandhi was killed by a female suicide assassin who strapped explosives to her body and detonated the bomb when she approached him with a garland of flowers.

A senior police source confirmed that one unidentified female victim appeared to have wires attached to her corpse.

The streets of the capital were largely deserted Wednesdayand most shops were closed. The U.S. Embassy told Americans to stay indoors.

Seven people were reported killed in violence nationwide. Dozens of towns were put under curfews, and dozens more observed voluntary strikes as a sign of respect for Gandhi.

More than 200 were killed in the campaign violence leading up to the election.

In Madras, 25 miles northeast of the remote town of Sriperambudur, where Gandhi was slain, angry crowds rampaged through the streets, looting shops and setting vehicles on fire.

Party spokesman Pranab Mukherjee said the Congress leaders unanimously chose Mrs. Gandhi at an hourlong meeting while her husband's body lay in state.

Her election was announced before she was informed of the decision, party leaders said.

Mukherjee said the decision by the party's 18-member, decisionmaking body was binding. "The question of acceptance does not arise," he said.

His body was flown to New Delhi Wednesday for an autopsy and embalming, then taken to the home of his grandfather and independent India's first prime minister, Jawaharlal Nehru.

The teak coffin, draped in the orange, green and white flag of the Congress Party, was brought past surging crowds straining at police barriers outside Teen Murti House, now a museum.

"It rained cats and dogs last evening - I thought it was an omen of Rajiv's coming back to power," said Rakesh Kumar, 29, holding back sobs. "Little did I know that God was shedding tears."

Mrs. Gandhi and the couple's daughter, Priyanka, both dressed in mourning white, accompanied the body. Gandhi's son, Rahul, has been studying in the United States and was returning home.

Police fired tear gas shells and charged with canes to hold back thousands of mourners. "Rajiv Gandhi is immortal!" shouted scores of people who had managed to break into the museum.

The caller who claimed responsibility for the assassination told the Times of India it was to exact revenge for minority groups in India and Sri Lanka who are seeking their own homelands, said the editor of the paper's southern regional bureau in Bangalore. He spoke on condition of anonymity.

"I can't say it is a hoax," Bangalore police Chief R. Ramalingam said. "But there is absolutely no clue at all about the identity of the killers from the statement."

The Liberation Tigers of Tamil Eelam, the largest Sri Lankan rebel group, issued a statement denying responsibility.

In 1987, Gandhi brokered a peace pact between Tamil rebels and the Sri Lankan government. The Tigers reneged on the pact and launched a guerrilla war against Indian peacekeeping troops who spent nearly three years in Sri Lankan trying to quell the Tigers.

Gandhi became prime minister in 1984 after his mother was assassinated. His party was ousted from power 18 months ago, and he was trying to make a political comeback at the time of his death.

Gandhi had been accused of being aloof in past campaigns. This time he changed his style and traveled to small towns and villages throughout the country, asking people for their votes.

Mrs. Gandhi often accompanied her husband on the hustings but stayed in New Delhi on Tuesday when her husband campaigned in the south.

Cremation is scheduled for Friday afternoon in New Delhi near Mrs. Gandhi's memorial on a bank of the Jamuna River.

*****

(Additional information)

Rajiv Gandhi: 1944 - 1991

Born: Aug. 20, 1944, in Bombay

Family: Married Italian-born Sonia Maino in 1968; 2 children.\ Education: Graduated in mechanical engineering from Trinity College, Cambridge, England, 1965.

Career highlights

1972-1981: Pilot for Indian Airlines.

June 1980: Becomes heir apparent to his mother, Prime Minister Indira Gandhi, following his brother Sanjay's death in an air crash.

1981: Elected to his brother's seat in parliament; becomes chief aide and adviser to his mother.

1983: Appointed as a general secretary of Indian National Congress; elected president of the party, 1984.

Oct. 31, 1984: His mother is assassinated by Sikh terrorists. In an emergency cabinet meeting, Rajiv is unanimously elected India's sixth and youngest prime minister; formally inaugurated after a landslide electoral victory in December.

1985: Visits the Soviet Union and obtains two new trade agreements; addrresses joint session of the U.S. Congress.

July 1985: Reaches agreement with Sikhs giving them greater political and economic influence in Punjab.

1986: Sikh-led Punjab government dismissed. Sikh insurgents remained a lingering problem to Ganhdi.

1987: Allegations surface that an arms company paid bribes to secure a government contract. Gandhi denies involvement and the government is cleared by a parliamentary committee, but an investigation presists.

1989: Charged with corruption and ousted by opposition.

May 21, 1991: Killed during an election rally in Sriperambudar, India.