* Q3 net profit 2.1 bln riyals vs 1.9 bln riyals yr-ago
* Impairment losses drop to 238 mln riyals in Q3
* Results slightly below analysts' forecasts (Adds details)
DOHA, Oct 7 (Reuters) - Qatar National Bank (QNB), the Gulf lender in talks to buy Societe Generale's Egyptian arm, posted a 10.5 increase in third-quarter net profit, driven by increased interest income and a drop in loan impairments.
The acquisitive bank, which has been snapping up stakes in small regional lenders, reported a net profit of 2.1 billion riyals ($577 million) for the third quarter, compared with 1.9 billion riyals a year ago, a bourse statement showed.
The results fell slightly short of analysts' average forecast of 2.2 billion riyals in a Reuters poll.
Banks in Qatar are expected to benefit as the country is one of the world's fastest-growing economies and set to spend more on infrastructure as it prepares to host the 2022 World Cup soccer tournament.
QNB, whose results are generally seen as an indicator for the sector's performance in the region, reported a nine-month net profit of 6.2 billion riyals, up 15 percent from a year earlier, it said in the statement.
Interest income rose to 3.1 billion riyals in the quarter from 2.6 billion riyals for the year earlier period. Impairment losses on loans and advances fell to 238 million riyals, compared with 250 million riyals the year before.
Total assets grew 25.3 percent during the nine-month period to 351 billion riyals, the highest ever achieved by the group, as a result of a 41.9 percent increase in loans and advances, the statement said.
QNB has been on an acquisition spree recently, buying stakes in regional lenders as it seeks to expand its footprint.
It is in talks with France's Societe Generale to buy its controlling stake in Egyptian unit National Societe Generale Bank.
QNB had been in the running earlier this year to acquire Denizbank, the Turkish unit of embattled Belgian lender Dexia, but in early June lost out to Russia's Sberbank, in a deal worth 3.09 billion euros.
In February, QNB issued a $1 billion five-year bond which was five times oversubscribed and received orders from more than 270 investors globally. [ID: nL5E8DF0AM]
The bank raised $3.5 billion from a rights issue last year.
QNB is 50-percent owned by sovereign wealth fund Qatar Investment Authority and has operations in Syria, Jordan, the United Arab Emirates and Switzerland.
Shares in QNB closed up 0.3 percent on the Doha bourse before the results were announced. They have dropped 1.9 percent year-to-date.
($1 = 3.641 Qatar riyals) (Reporting By Regan Doherty, Editing by Dinesh Nair and Mark Potter)