* Q3 profit 70 mln dinars vs 108.1 mln dinars yr-ago -Reuters calculation
* Adjusted profit, excluding one-off gain, up 34.7 pct
* CEO says domestic operating environment improving (Adds details, CEO comments)
DUBAI, Oct 23 (Reuters) - National Bank of Kuwait (NBK), the Gulf Arab state's largest lender, reported a 35.3 percent fall in its third-quarter net profit on Wednesday, Reuters calculations show, mainly due to a one-off gain recorded in the year-ago period.
Net profit for the three months to the end of September 30 was 70 million dinars ($248.4 million), compared with 108.1 million dinars in the corresponding period in 2012, Reuters calculated from the bank's previous financial statements.
The profit slightly missed the average estimates of six analysts who had predicted a quarterly profit of 72.3 million dinars.
NBK's nine-month net profit was 198.6 million dinars compared with 228.9 million dinars a year ago, it said in an emailed statement.
The lender recognised exceptional gains of $288 million during the year-ago period because of the consolidation of results of Boubyan Bank, it said in the statement. Excluding the gain, net profit for the nine-month period rose 34.7 percent, NBK said. It did not provide quarterly figures.
The domestic operating environment continues to improve and the overall outlook is more positive, NBK's long-serving Chief Executive Ibrahim Dabdoub said in a statement.
"We have started witnessing some acceleration in the tendering, award and execution of some of the large projects as the government proves determined to advance the execution of the development plan," Dadboub said.
Kuwait's 30 billion dinar economic development plan, announced in late 2010, has been delayed by political infighting and chronic bureaucracy.
A more stable political environment since late last year had fuelled hopes that Kuwait will push ahead with huge infrastructure projects in the plan, to the benefit of local companies.
NBK's loans and advances by the end of September reached 10.5 billion dinars, up 9.3 percent from year-ago period and customer deposits reached 10 billion dinars, up 16 percent year-on-year, the lender said. ($1 = 0.2819 Kuwaiti dinars) (Reporting by Praveen Menon; Editing by Dinesh Nair)