LONDON, Feb 13 (Reuters) - NatWest will buy an 85% stake in workplace savings account provider Cushon for 144 million pounds ($174 million), the British bank said on Monday, as it seeks to grow its product offering to businesses.

Cushon's primary products are savings accounts and pensions, NatWest said, allowing the bank to offer a new range of financial products to commercial customers and to their staff.

British banks have in recent years stepped up their acquisitions of smaller financial technology firms as they try to broaden their product range, appeal to younger customers, and compete with more nimble digital rivals.

NatWest Chief Executive Alison Rose last year said the bank was on the hunt for such deals, especially in the wealth management sector.

Cushon products will at first be offered to NatWest's mid-market corporate customers, following a succesful test last year, the lender said.

The deal will close later this year and is subject to regulatory approval.

($1 = 0.8264 pounds) (Reporting by Lawrence White; Editing by Jan Harvey and Mark Potter)