Rajiv Gandhi said Thursday he turned down an offer to form a new Indian government and that he would support the claim of veteran socialist Chandra Shekhar.

"We are not forming the government because we do not have an adequate mandate," said Gandhi, whose Congress party lost its majority in last November's elections. "We have decided to support Mr. Chandra Shekhar."Gandhi said he had sent the decision to President Ramaswamy Venkataraman, who asked him to form a government earlier on Thursday following the crushing parliamentary defeat of Prime Minister Vishwanath Pratap Singh in a confidence vote.

Gandhi said he turned down the prime ministership after a meeting of the Congress Party parliamentary board.

His refusal considerably strengthened the claim of Chandra Shekhar, who split Singh's Janata Dal Monday after weeks of violence that finally toppled the minority government Wednesday night.

Singh formally quit office Thursday morning when his resignation was accepted at a meeting with Venkataraman.

"I am out of the government," said Singh.

Venkataraman has made it known he is unhappy with the idea of a government headed by Shekhar, who commands only 56 votes in the 545-member parliament.

Shekhar thought he had gained the prime ministership last December, only to discover a deal behind his back gave the job to Singh.

He has scowled and growled on the sidelines over the past 11 months, leaving no one unaware of his dislike of Singh and at least twice tried to organize a rebellion against him.

Shekhar succeeded in splitting the Janata Dal when it became clear Singh favored early elections over a caste-based job quota plan and a Hindu militant campaign to replace a 16th century mosque in the northern holy town of Ayodhya with a temple.

The two issues unleashed weeks of violence. More than 200 people were killed last week in Hindu-Moslem clashes set off by the temple campaign.