An overwhelming majority of Americans favor a ban on semiautomatic assault weapons, although there is no consensus on how such a ban should work, according to two polls released Saturday.

A nationwide survey conducted by the Los Angeles Times found that 80 percent of Americans favored banning such weapons. A Newsweek poll showed that 72 percent favor a permanent ban on selling them, while 21 percent opposed such a ban.The Times poll found opposition to the sale and possession of the rapid-firing weapons across political, ethnic, gender, geographical and educational lines, said survey director I.A. Lewis.

However, given several suggestions for how to remove the guns from society, respondents split three ways. Twenty-four percent said the guns should be confiscated from present owners, 30 percent supported buying the guns back and 30 percent would allow present owners to keep their guns but ban new sales.

More than half of the 1,158 people polled in the Times' telephone survey said only law-abiding citizens would obey the ban, leaving the weapons mainly in the hands of criminals.

The poll has a margin of error of plus or minus 3 or 4 percentage points, Lewis said.

According to the Newsweek poll, 58 percent of Americans believe a ban would reduce the number of killings by unstable people, the magazine said. However, half of those polled said they did not believe such a ban would reduce drug- or crime-related killings, while 45 percent said they believe it would help.

Seventy-eight percent of those surveyed said they believe people should be required to provide more information to police before they are allowed to buy any kind of firearm, while 15 percent said they believe current laws are adequate.

The telephone poll of 756 adults was conducted March 16-17 and has a margin of error of plus or minus 4 percent.