Largest Canadian insurer Manulife Financial Corp's (MFC.TO) U.S. unit will buy New York Life Insurance Co's retirement services business for an undisclosed amount.

New York Life will also assume 60 percent of certain life insurance policies of Manulife's U.S. unit, John Hancock Financial, on a reinsurance basis, the Canadian company said.

The deal, expected to close in the first half of 2015, will increase John Hancock's retirement plan assets under administration by 60 percent to about $135 billion.

The combined business will have 2.5 million plan participants, Manulife said.

Manulife and Britain's Standard Life (SL.L) agreed in September to a near-$4 billion deal for the Canadian operations of the British insurer as part of a broader global tie-up.