Singapore won a bitterly-fought match 2-1 on Wednesday after the Thai players walked off the field for 15 minutes following a controversial penalty award to Singapore eight minutes from time. Singapore eventually scored the penalty and won 2-1.

The Guardian reported that anyone found guilty of orchestrating the protest or manhandling the referee could be banned from the second leg in Bangkok on Sunday.

"The Asean Football Federation are studying the relevant reports from the match commissioner and referees inspector," an AFF spokesman said.

"Based on the records action will be taken against anyone guilty of wrong-doing in the 1st leg."

A capacity crowd at the National Stadium booed and jeered as the Thai team walked, preventing the penalty being taken.

Their tempers flared after Singaporean striker Noh Alam Shah went down in the area and the Malaysian referee pointed to the spot.

The players eventually returned after 15 minutes and Mustafic Fahrudin fired the penalty high into the roof of the net to put Singapore 2-1 ahead.

The walkout came amid growing bad blood between the two countries following last year's takeover by Singapore state investment arm Temasek of telecoms firm Shin Corp, founded by ousted Prime Minister Thaksin Shinawatra.

Temasek's $3.8 billion acquisition of Shin Corp added fuel to anti-Thaksin street protests that led to his removal in a bloodless military coup on Sept. 19.

A spat erupted two weeks ago when Bangkok summoned the Singaporean ambassador to protest a meeting between Thaksin and one of the city-state's senior cabinet ministers.