* Deposits at end-June 2.46 bln rials, down 12 pct
* Deposits of state firms at Omani banks down in April
* Analysts point to impact of falling oil prices (Recasts, adds analyst comment, context)
DUBAI, July 14 (Reuters) - National Bank of Oman, the country's third-largest bank by assets, reported a 21.4 percent rise in second-quarter profit on Tuesday, but also revealed a 12 percent decline in customer deposits during the first half of the year.
NBO's deposits dropped to 2.46 billion rials ($6.39 billion) at the end of June, down from 2.78 billion rials in the same period last year.
Aarthi Chandrasekaran, an analyst with NBK Capital, said this could reflect the impact of falling oil prices.
"Deposits at NBO have been choppy in recent quarters," he said. He said the deposit drop at NBO was not too much of a concern as long as deposit growth could stay ahead of loan growth in the coming quarters.
Government finances in the oil-exporting Gulf states have been hit by the fall in oil prices in the past year. Crude oil prices dropped from $115 a barrel in June 2014 to a low near $45 in January. They have since recovered some ground but are still close to half their peak last year.
Oman reported a budget deficit of 544.6 million rials ($1.41 billion) in the first three months of this year, swinging from a 215.4 million rial surplus a year earlier.
Government deposits account for 28 percent on average of total bank deposits in the Gulf, according to a recent report by Standard & Poor's on the impact of falling oil prices on the banking systems of oil producers.
NBO's deposit drop also coincides with a fall in deposits of state-owned firms at Omani banks. They totalled 822.3 million rials for April, down from 1.09 billion rials in the corresponding period of last year, according to latest central bank data.
Deposits at Oman's two largest banks by assets rose in the first half. Deposits at Bank Dhofar rose by 19.73 percent to 2.63 billion rials, while deposits at Bank Muscat rose by 14.2 percent to 7.42 billion riyals.
Bank Dhofar reported rises in second quarter profit, while Bank Muscat's profit was marginally lower.
NBO's 21.4 percent rise in second-quarter net profit to 15.46 million rials, according to Reuters calculations, beat analysts' estimates. Loans and advances stood at 2.43 billion rials at the end of June, 10 percent higher year-on-year.
The government of Oman is NBO's second largest shareholder with a stake of 24.8 percent, according to Thomson Reuters data. Commercial Bank of Qatar holds a 34.9 percent stake, the same data shows.
Reporting by Tom Arnold and David French; Editing by Andrew Torchia and Jane Merriman