LOS ANGELES, May 2 (Reuters) - The Los Angeles Police Department will investigate officers who used batons and rubber bullets to disperse protesters and journalists at the end of daylong immigration rallies, chief William Bratton said on Wednesday.

Rally organizers criticized police for heavy-handed tactics after videotapes of the incident showed a line of officers in riot gear clearing demonstrators from the city's MacArthur Park with batons and rubber bullets.

The local Radio and Television News Association also demanded an investigation into the treatment of reporters at the scene, saying that several had been pushed to the ground or struck by police and that their equipment had been damaged.

Bratton said he would investigate the actions of officers at the scene, who moved in to clear the park after a small band of protesters created a disturbance, reportedly pelting police with rocks and bottles.

"Quite frankly, I'm disturbed at what I saw," Bratton told KNX-AM radio. "Some of the officers' actions ... were inappropriate in terms of batons and possible use of non-lethal rounds fired."

A police spokeswoman said the department would have no further comment pending a news conference scheduled by Bratton for later on Tuesday.

The videotaped clash between officers, protesters and journalists was shown repeatedly on television in Los Angeles, where police have struggled to overcome a reputation for using excessive force.

In 1992 the city erupted into riots following the acquittal of four police officers in the videotaped beating a year earlier of black motorist Rodney King.

Some 25,000 people marched through the streets of Los Angeles on Tuesday as part of nationwide protests intended to demonstrate the political might of Latinos and help win amnesty for illegal immigrants.

The May Day demonstrations attracted much smaller crowds than last year.

The rallies come as U.S. lawmakers seek to write a bill to provide tougher border control and workplace enforcement while addressing the status of illegal immigrants.

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