NEW DELHI, India (AP) _ Officials threw out thousands of parliamentary election ballots Thursday as the governing party and the opposition traded charges of fraud, voter intimidation and violence. Forty-eight people have been killed.

The election commission also ordered an investigation into charges of widespread vote-rigging in the constituency where Prime Minister Rajiv Gandhi is seeking re-election on the ticket of his Congress Party.

Security forces braced for more violence in the 10 states and two federally ruled territories that began voting Friday, the second of the three-day polls.

Authorities in particular feared violence in northern Bihar, an impoverished state with a reputation for corruption and ''fistfight democracy.'' Polls opened Friday in Bihar and voting was to continue on Sunday, the last day of the election.

At least 92 people, including three independent candidates, have been killed since elections were announced Oct. 17, the ninth since India won independence from Britain in 1947.

Gandhi appealed to Indians to refrain from violence in the final two days of voting.

''There is no place for violence in our democratic system,'' the prime minister said a news conference in Uttar Pradesh, where he went to see a former ally critically wounded in a shootout a day earlier. He later called off the visit, fearing tensions with opposition supporters.

The National Front, a loose-knit coalition of five opposition parties, accused Gandhi and his Congress Party of engineering the violence.

''His intentions are most suspect and he is up to all kinds of mischief, including murder - of individuals and democracy,'' said Yashwant Sinha, a spokesman for the Janata Dal (People's Party), the main force in the National Front.

Gandhi, who was propelled to power hours after the 1984 assassination of his mother and predecessor, Prime Minister Indira Gandhi, has been the main issue in the monthlong campaign. The opposition's plank has centered around the 45-year-old prime minister's alleged corruption and ineptitude.

The Congress Party has sought to portray the elections as a choice between stability and chaos, maintaining the opposition's newly found unity will quickly shatter if it is voted to power. But opinion polls show Gandhi and his party are in serious trouble and in danger of losing.

At stake are 524 of the 543 seats in the Lok Sabha, or House of the People, the law-making lower house of Parliament. Several races have been postponed because of incomplete voter rolls and candidates' deaths.

Voting ends Sunday, but the results are not expected until Sunday night and Monday.

The Election Commission tossed out thousands of suspected fraudalent ballots cast Wednesday at more than 600 polling booths in six states and sent a team to investigate charges of vote fraud in the Amethi constituency, where Gandhi is facing Raj Mohan Gandhi, the grandson of India's beloved independence leader Mohandas K. Gandhi.

Anand Sharma, the Congress Party's chief spokesman, labeled the opposition charges as ''another orchestrated drama to malign the prime minister'' and ''a smokescreeen to cover the brutal and ferocious assaults'' by the opposition.

Among those injured in Wednesday's violence was Sanjay Singh, an opposition leader who was Gandhi's campaign manager in the December 1984 elections. He defected to the opposition two years ago with his wife's uncle and the man expected to become prime minister if the opposition wins, Vishwanath Pratap Singh.

According to the National Front, Sanjay Singh was wounded during a shootout Wednesday during voting in Amethi constituency, a remote rural area in northern Uttar Pradesh state. Two opposition workers also were wounded, one of them seriously.

The prime minister said he had asked the Uttar Pradesh government to thoroughly investigate the shooting but denied Congress Party workers were responsible for the shooting.

''It is not in the interest of the party to introduce violence in the polling because the majority of voters are voting for us,'' he said.

Sanjay Singh was unconscious and in critical condition at a hospital in the state capital of Lucknow following a three-hour operation to remove bullets from his stomach.

''He is still with us, but hovering between life and death,'' Sinha told a news conference in New Delhi.

L.C. Jain, the campaign manager for Raj Mohan Gandhi, said Congress Party ''goons, hoodlums and gangsters took over polling booths'' in Amethi constituency and stuffed ballot boxes. He and other opposition politicians and supporters asked the Election Commission to invalidate the ballots and order another poll.

Sharma, the Congress Party spokesman, dismissed the request. ''The people have voted. There is no need to interfere,'' he said.

Election Commissioner R.V.S Peri Sastri said a special team had been sent to Amethi to investigate allegations of vote rigging.

''We will withyhold the results from Amethi until the inquiry is completed,'' said Sastri, who noted the commission had received complainits of fraud and violence ''from almost all'' the 221 constituencies that conducted polls Wednesday. No date was set for the new polls.