Sept 21 (Reuters) - Four former heads of the U.S. Environmental Protection Agency, Democrats and Republicans, on Monday issued a sharp rebuke of the Trump administration's record on the environment after the current administrator said the agency is focused on "work that has been neglected for years."

Former EPA administrators for Democratic presidents Barack Obama and Bill Clinton and Republicans George H.W. Bush and his son George W. Bush criticized the administration of President Donald Trump for rolling back regulations on methane, vehicle emissions and power plants.

"If you need any more proof of how strongly this is felt by people you have it today in four former administrators... we've all come to the same conclusion," Carol Browner, who ran the EPA under Clinton, told reporters in a call organized by Joe Biden's presidential campaign.

Two Republican former administrators, William Reilly and Christine Todd Whitman, endorsed Biden on the call, saying the Trump administration's actions on the environment had been an "aberration."

"There has been nothing like an administration, on the environment, in the last 50 years to compare with the dereliction that characterizes this administration," Reilly, who served under George H.W. Bush, said on the call.

Earlier on Monday, Trump EPA Administrator Andrew Wheeler said in a speech at the American Enterprise Institute, a conservative think tank, that the environment has improved during his tenure as the agency focused on what he called its core work, such as cleaning up Superfund sites.

"We have done more in the first four years of the Trump Administration to improve the environment than probably any administration except perhaps during the very first years of EPA," he said, accusing his predecessors of focusing too much on climate change and "virtue signaling" to foreign capitals.

In the coming weeks Wheeler said EPA will propose rules to limit lead in drinking water.

Whitman, who served under George W. Bush, was asked to react to Wheeler's claim that the environment had improved under Trump.

"If we could substitute 'destroy' for the word 'improve' he'd be right on," she said. (Reporting by Nichola Groom and Valerie Volcovici; editing by Timothy Gardner)