DOHA- Qatar Airways reported a loss of 2.3 billion Qatari riyals ($639 million) on Wednesday for the year ending March 31, as it grappled with the second year of an embargo by neighbours that has restricted its air routes and driven costs higher.

The results mark a steeper loss from the previous year when the company was $69 million in the red.

Group Chief Executive Akbar Al Baker said in a statement that the losses were attributable to "loss of mature routes, higher fuel costs and foreign exchange fluctuations" but said underlying fundamentals "remain extremely robust".

Saudi Arabia, Egypt, the United Arab Emirates and Bahrain cut diplomatic and economic ties with Qatar in June 2017 and Qatar Airways has since been banned from flying to the four countries and from using their airspace.

The country's flagship airline has looked to mitigate the impact of the dispute by launching flights to new destinations, increasing flights on existing routes, and leasing aircraft to other airlines.

It launched 11 new destinations during the previous fiscal year, bringing a total of 31 new destinations online since the start of the embargo, the statement said.

"Despite facing challenges that are unparalleled in the airline industry, I am very proud that we have grown our fleet, expanded our network and seen overall revenue increase to QAR 48 billion ($13.2 billion), a rise of 14%," said Baker.

The state-owned carrier purchased a 5% stake in China Southern Airlines 600029.SS during the fiscal year, helping it gain access to the fast-growing mainland Chinese market.

It also holds minority stakes in British Airways-parent International Airlines Group (IAG) South America's LATAM Airlines Group, Hong Kong's Cathay Pacific Airlines, and China Southern Airlines.

(Reporting by Eric Knecht, editing by Deepa Babington and Elaine Hardcastle) ((eric.knecht@thomsonreuters.com; +20 2 2394 8102; Reuters Messaging: eric.knecht.thomsonreuters.com@reuters.net))