DUBAI, April 18 (Reuters) - Commercial Bank of Qatar (CBQ), the Gulf Arab state's third-largest lender by assets, reported a 68.3 percent drop in first-quarter net profit on Tuesday, missing analysts' forecasts, as bad debt charges rose sharply.

The bank earned a net profit attributable to equity holders of 91.2 million riyals ($25.1 million) in the three months to March 31, it said in a statement. That compares with a profit of 288.1 million riyals in the same period a year earlier.

That was below the average forecast of three analysts polled by Reuters, who had expected the bank to report a net profit of 209.4 million riyals.

The bank earned net profit, inclusive of non-controlling interests, of 91.2 million riyals for the first quarter, compared with 274.2 million riyals in the same period of last year.

The bank, which completed a 1.5 billion riyals rights issue in the first quarter, was hit by a 84.7 percent rise in net provisions for loans and advances to 478.7 million riyals.

CBQ has had to contend with a rise in bad loans linked to troubles facing some of its overseas investments, as well as cutbacks in state and consumer spending in Qatar.

CBQ last year raised its stake in Turkey's Alternatifbank to 100 percent and also holds shares in National Bank of Oman and United Arab Bank. UAB on Sunday reported a 38 percent fall in first-quarter net profit to 28 million dirhams ($7.6 million), although impairment losses dropped 51 percent over the same period.

In a statement, CBQ chief executive Joseph Abraham said provisions would remain elevated for the next few quarters as the bank continued to ensure it had adequate provisions against its loan book.

Abraham launched a five-year plan in November to try to stem a dismal earnings run that has included five quarters of falling profits and one net loss in the past six quarters.

Loans and advances stood at 82 billion riyals at the end of March, up 8.6 percent on the same point of 2016. Lending growth was mainly driven by services, consumption and industry sectors, it said.

($1 = 3.6410 Qatar riyals)

($1 = 3.6730 UAE dirham)

(Reporting by Tom Arnold; Editing by Mark Potter) ((Tom.Arnold@thomsonreuters.com; +97144536265; Reuters Messaging: tom.arnold.thomsonreuters.com@reuters.net))