(Reuters) - MetLife Inc , the largest U.S. life insurer, has put its British bulk annuity business, MetLife Assurance Ltd, up for sale and has hired investment bankers from Citibank to run an auction for the unit, a person familiar with the matter said.

The source, who is not authorized to speak to the media, said MetLife had begun a sale process for the business -- which employs 55 people -- and was talking to several potential buyers.

The sale does not include MetLife's other British businesses, the source said.

Sky News first reported the planned sale and said it was unclear how much MetLife was seeking for the business. But Sky News, citing people close to the situation, said the price tag would be far below the 1 billion pounds ($1.53 billion) suggested by some analysts,

"We do not comment on market rumours or speculation," MetLife said.

Last month, MetLife closed the sale of its deposit-taking business to General Electric Co , a move that paved the way for the company to deregister as a bank holding company. This helps reduce scrutiny from the U.S. Federal Reserve and frees up capital to pay dividends or buy back shares.

(Reporting by Abhishek Takle in Bangalore; editing by John Wallace)