Thailand's stock market is set to post net foreign outflows in May, its first since November, as the European debt crisis unnerved investors.

Foreign investors were net sellers of $505 million worth of Thai stocks in May until Tuesday, after being net buyers over the past five months (December-April 2012) for a combined $3.1 billion, data from Thomson Reuters shows.

Fund flows were mixed in other Southeast Asian bourses. Indonesia posted $702 million in net foreign outflows so far in the month to Tuesday after taking in a total of $1.1 billion for two straight months to April, data shows. The net outflows in Indonesia in May were the biggest since August.

Net foreign outflows of Philippine stocks totalled $243 million for May until Tuesday after net inflows of $107 million in April.

Vietnamese stocks eked out $0.14 million in inflows in the same period after April's $35 million in outflows.

1545 (0845 GMT) (Reporting by Viparat Jantraprap in Bangkok; viparat.jantraprapaweth@thomsonreuters.com)