DUBAI - Riyad Bank, Saudi Arabia's fourth-largest lender by assets, posted a huge rise in fourth-quarter net profit on Tuesday, beating analysts' forecasts, boosted by an easing of impairment charges for credit losses.

The bank made 974 million riyals ($259.7 million) in the three months to Dec. 31, up from 293 million riyals in the same period of 2016, it said in a bourse filing.

Three analysts polled by Reuters had on average forecast the bank's quarterly profit at 732.1 million riyals.*:nL8N1PW0K4

The bank attributed the performance to a 29.2 percent drop in total operating expenses, mainly due to a dip in impairment charges.

Operating income was also 12.3 percent higher over the same period, helped by an increase in net special commission income, gains on non-trading investments and fee and commission income.

After having their performance clipped by the impact of lower oil prices, banks have been aided by an improvement in liquidity in recent months. Lenders should be further boosted by a pick-up in lending in 2018 as the government embarks on a stimulus of 72 billion riyals to support private-sector growth over the next four years.

Riyad Bank's loans and advances at end-December fell 2.9 percent on year, while deposits dipped 1.5 percent over the same period.

The bank has been hit by a contraction in lending and deposits for each quarter since the third quarter of 2016. ($1 = 3.7502 riyals)

(Reporting by Tom Arnold; Editing by Sunil Nair) ((; +97144536265; Reuters Messaging: