(Reuters) - Blackstone Group LP, the world's largest manager of alternative assets, on Tuesday reported an average gender pay gap of 30 percent at its UK business, a rare insight into the private equity industry's wage disparities.

Blackstone said on Tuesday that the gap chiefly comes from men occupying the bulk of high-paying investment jobs at the firm.

"As these roles typically attract higher rewards than non-investment roles, this increases the average pay for male employees," New York-based Blackstone said.

"In contrast, less than a fifth of our female employees are investment professionals and nearly three quarters are in support and administrative roles."

The disclosure was made to comply with a UK government directive for employers with more than 250 staff to report their gender pay gap by April 4.

The disparity at Blackstone was far greater in bonuses, which often go to more senior employees, with a mean gap of 75 percent.

Blackstone said it was confident women and men were paid equally for equivalent jobs across its business.

But the numbers underscore how private equity remains a male-dominated industry.

Gender diversity has improved since private equity rose to prominence on Wall Street in the 1980s and Blackstone now staffs around 40 percent of its incoming analyst class with women, a source familiar with the matter said. Analyst classes can filter up into more senior positions.

Nevertheless, top management at the largest firms, which include Blackstone, Apollo Global Management LLC, KKR & Co LP (>> KKR & Co. L.P.) and Bain Capital LLC, are largely male and the lack of diversity is often visible at industry events.

Speaking at an annual private equity get-together in Berlin earlier this year, ex-Greek finance minister Yanis Varoufakis joked, "gender balance is an issue in this room".

The #MeToo movement has also put new momentum behind efforts to have companies, especially in finance, disclose details about their workforce diversity.

Citigroup, Bank of America Merrill Lynch (>> Bank of America), Credit Suisse and Morgan Stanley last month all revealed large gender pay gaps in their British operations.

In January, Blackstone agreed to buy a majority stake in the Financial and Risk business of Thomson Reuters Corp  (>> Thomson Reuters Corp), the parent of Reuters News, in a $20 billion deal. Reuters News will remain part of Thomson Reuters.

(Reporting by Joshua Franklin in New York, Editing by Rosalba O'Brien)

By Joshua Franklin