* Q1 net profit 1.71 bln riyals, down 16.9 pct
* Misses analysts' forecasts of around 2.05 bln
* Third quarter of declining profits
* Higher provisioning is likely cause of profit drop
* Contrasts with strong Q1 at some other Saudi banks (Adds detail, context, analyst comment)
By David French
DUBAI, April 13 (Reuters) - Al Rajhi Bank reported a slump in net profit for the first three months of 2014 on Sunday, marking the second quarter in a row that Saudi Arabia's largest listed lender has posted a big decline in earnings.
The bank made 1.71 billion riyals ($456 million) in the three months to March 31, down 16.9 percent from 2.05 billion riyals in the same period a year earlier, it said in a bourse filing.
Analysts surveyed by Reuters had expected the bank to post an average net profit of 2.05 billion riyals for the quarter.
Al Rajhi said in Sunday's statement that the profit drop was due to an increase in operating expenses; it did not elaborate. Saudi companies issue brief earnings statements early in the reporting period before publishing more detailed results later.
An increase in operating expenses is usually interpreted by analysts to mean higher provisioning for bad loans. Naveed Ahmed, senior manager at Global Investment House, estimated Al Rajhi had posted a roughly 50 percent year-on-year increase in provisions.
"We believe that the results were disappointing and that the bank's asset quality requires more reading into," he said in a research note.
Labour market reforms in Saudi Arabia, making it more expensive to hire foreign workers and therefore pushing up companies' costs, have hurt the profits of construction firms and prompted some banks to increase their provisions for exposure to the construction sector. It was not clear whether this was a factor in Al Rajhi's latest earnings decline.
Al Rajhi's fourth-quarter net profit dropped 19.1 percent, which was also due to increased impairment allowances. The bank reported a drop in profits for the third quarter of last year, albeit a marginal one.
The decline in first-quarter earnings at Al Rajhi contrasts with positive results reported by some other Saudi banks.
Riyad Bank and Saudi British Bank posted profit growth of 13.5 and 14 percent respectively, while Banque Saudi Fransi's first-quarter profit jumped 25 percent after a big drop in fourth-quarter earnings.
Al Rajhi's earnings decline in the opening three months came despite modest year-on-year increases in operating income and profit from special commissions.
Loans and advances stood at 193.1 billion riyals on March 31, up 7 percent on the same point in 2013. Customer deposits rose 2.9 percent over the same time frame to 238.5 billion riyals. ($1 = 3.7502 Saudi Riyals) (Editing by Andrew Torchia)