DUBAI  - Commercial Bank of Qatar , the Gulf Arab state's third-largest lender by assets, beat estimates with a five-fold increase in second-quarter net profit on Thursday as provisions for bad loans fell by more than half.

Net profit for the three months to June 30 jumped to 450.4 million riyals ($123.7 million) from 88.4 million riyals a year earlier and topped the 409.0 million expected by three analysts polled by Reuters.

The results mark a fourth consecutive quarter of profit jumps for the bank, which until last year was setting aside additional provisions to cover bad debt linked to troubles facing some of its overseas investments, as well as cutbacks in state and consumer spending in Qatar.

Provisions for loans and advances fell by 57 percent to 206.4 million riyals.

Net interest income rose 6.3 percent to 669.2 million riyals and net fee and commission income rose 5.6 percent to 187.9 million riyals.

It is the fourth major Qatari bank to report earnings for the period and the second to beat earnings after Qatar Islamic Bank, which reported a 14.8 percent jump in second-quarter net profit.

Qatari banks have sought to diversify funding sources since a political dispute erupted in June 2017 between Qatar, Saudi Arabia, United Arab Emirates, Bahrain and Egypt.

In the second quarter, Commercial Bank issued the first public bond by a Qatari bank since the row began. 

It issued a $500 million bond under its European Medium Term Note programme, which the bank said was twice oversubscribed, indicating international investor confidence in the strength of the Qatari economy and the bank's growth prospects.

($1 = 3.6405 Qatar riyals)

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