SINGAPORE - Philippines emerged as the region's sprint kings after winning the men's and women's 100m races on Tuesday, but were left embarrassed when it turned out they had been wearing the Philippines' national flag upside-down.

The track attire of men's champion Eric Cray and women's winner Kayla Richardson both sported an upside-down version of the flag - with the red rather than blue on top - sparking a minor outcry back home.

According to Filipino website Inquirer.net, the inverted colours mean that the country is officially at war.

It is not yet known who was responsible for the gaffe.

Philippines presidential spokesman Abigail Valte was quoted as saying that she hoped the error would be rectified.

She said: "It must have been an oversight."

Both athletes are of Filipino heritage despite having spent most of their lives in the United States.

Cray, 26, who took the gold at Singapore's National Stadium in a personal best time of 10.25sec, has qualified for the 2016 Olympics.

He switched to representing the Philippines in 2011.

Richardson, meanwhile, has only been in the country once for a holiday. The 17-year-old won her race in 11.76sec, finishing ahead of Thailand and Singapore's Shanti Pereira.

It is not the first time such an incident has occurred.

In 2013, Seattle Seahawks wide receiver Doug Baldwin carried a Filipino flag upside-down as he campaigned for the victims of Typhoon Haiyan.

And in 2010, the US had to apologise after President Barack Obama led a meeting of world leaders which also featured an inverted Philippines flag.