Dec 16 (Reuters) - National Australia Bank on Wednesday said it had agreed to sell its New Zealand life insurance business to Partners Life for NZ$290 million ($206.10 million), as part of its strategy to increase capital and focus on core banking operations.

Australian lenders have been on a selling spree, hiving off underperforming insurance assets to re-focus on lending operations and reduce regulatory troubles amid increased scrutiny into the sector after a series of scandals.

Earlier this month, Westpac Banking Corp, the country's second-largest lender, agreed to sell its general insurance arm to German insurer Allianz for A$725 million ($535 million).

The sale of BNZ Life to the New Zealand-based insurer would result in an increase in NAB Group's Common Equity Tier 1 ratio by 6 basis points, based on its risk weighted assets as at Sept. 30, the lender said in a statement.

As part of the sale, BNZ will also enter into an exclusive 10-year agreement for the referral of its customers with life insurance needs to Partners Life, the lender said.

In recent months, NAB sold its wealth management unit to IOOF Holdings for $1.1 billion and also sold its entire broker aggregation business, with a number of other smaller units under the lens for a possible sale. ($1 = 1.4071 New Zealand dollars) (Reporting by Rashmi Ashok in Bengaluru Editing by Shri Navaratnam and Sam Holmes)