LONDON (Reuters) - Investors looking for companies with good environmental, social and governance track records will find the job easier after European politicians ruled that thousands of firms must reveal their performance as corporate citizens.

Trillions of dollars of pension fund, insurer and mutual fund money is already invested in companies that are screened for a range of ethical criteria because of evidence that such firms tend to be more profitable in the long term.

Until now, the release of information has been patchy. The new legislation, though watered down from initial proposals, will compel around 6,000 mostly listed firms across the European Union to provide details on how they tackle issues such as bribery and human rights.

"We're very, very pleased with the outcome; we think it will make a big difference," said Steve Waygood, chief responsible investment officer at Aviva Investors, the fund management arm of the UK insurance group, which has 241 billion pounds (S$507 billion) in assets under management.

"This really is an eleventh-hour agreement ... we were very concerned that nothing would have been agreed at all and that this would have been knocked back three or four years and that a great deal of work would have been wasted," he added.

The legislation, which still needs to be approved by EU member states, will require companies to disclose information on environmental, social, employee, human rights, corruption and bribery matters in their management reports.

What this looks like in practice has yet to be hammered out and could vary. The rules do not prescribe the information to be given.

Matthew Doyle, director of Hermes Equity Ownership Services, said the rules would "start important new developments in corporate reporting" and enable investors to access "materially important" information that would help them to better evaluate the sustainability of companies' operations.

A January report by fund manager Hermes found that well governed companies had outperformed returns on the poorly governed by an average of over 30 basis points over the past five years.