LONDON, Jan 31 (Reuters) - Monument Re's shareholders have launched a sale process that could see a private equity group take control of the company, three people familiar with the matter told Reuters.

U.S. insurer Enstar Group, Monument Re Chairman Jonathan Yates and Caspar Berendsen, former financial services head at private equity firm Cinven, are expected to sell shares to a new majority investor, which will also inject fresh capital into the business, the people, who spoke on condition of anonymity, said.

Another shareholder Hannover Re, however, is not planning to sell shares at this time, they added.

Enstar and Yates did not reply to requests for comment. Berendsen and Hannover Re both declined to comment.

Monument Re buys old life insurance portfolios from the likes of AXA and Allianz and has operations in several European countries.

Reuters reported in August that Monument Re's owners had appointed advisers at Citi and Fenchurch Advisory to explore strategic options after witnessing a drop in the company's capital ratios.

The efforts come as regulators step up their scrutiny of life insurance, with bodies, such as the International Monetary Fund raising concerns over private capital's growing role in the sector.

Last year, Italy orchestrated a rescue of life insurer Eurovita after its private equity owner Cinven failed to prevent its collapse.

Monument Re's owners distributed marketing materials among prospective bidders earlier in January, formally kicking off the sale, the people familiar with the process said.

Among those invited were alternative asset managers with existing insurance platforms, including Brookfield, Carlyle, KKR and Sixth Street, the people said. (Reporting by Pablo Mayo Cerqueiro and Amy-Jo Crowley in London; Editing by Anousha Sakoui and Tomasz Janowski)