Southeast Asian foreign ministers on Wednesday expressed concern at Chinese land reclamation in the disputed South China Sea, as the Philippines urged them to stand up to Beijing.

The statement came after Manila warned fellow members of the Association of Southeast Asian Nations (ASEAN) at a ministers' retreat in Malaysia that the 10-country grouping's credibility was at stake unless it dealt strongly with the "critical issue in our own backyard".

"The retreat shared the concern raised by some foreign ministers on land reclamation in the South China Sea," said a statement by the gathering's host, Malaysian Foreign Minister Anifah Aman, following the two-day meeting.

It mentioned no specific countries.

Wary of upsetting relations with its giant neighbour to the north, ASEAN has for years responded cautiously to China's increasingly assertive moves to stake its claims in the South China Sea.

China claims almost all of the sea, a position that conflicts with ASEAN members Brunei, Malaysia, the Philippines and Vietnam, as well as with non-member Taiwan.

Beijing has sparked growing alarm around the region with actions viewed as aggressive, raising fears of conflict.

Philippine foreign minister Albert del Rosario said last week Beijing was trying to construct islands around isolated reefs in the Spratly islands, which could hold fortified positions or even airstrips.

"The massive reclamation issue presents a strategic policy dilemma for ASEAN," he said in a statement Wednesday.

"Our inaction on this would undermine (ASEAN unity), since we are unable to address in a unified and collective way such a critical issue in our own backyard."

He also said the international community must "say to China that what it is doing is wrong -- that it must stop its reclamation activities at once".

The foreign ministers met in the city of Kota Kinabalu on Borneo island -- on the shores of the disputed waterway -- in the first of several diplomatic gatherings this year in Malaysia, which holds the ASEAN chair for 2015.

Anifah's statement called on ASEAN to step up efforts to achieve implementation of a code of conduct in the South China Sea aimed at preventing conflict.

After years of pressure, China agreed in 2013 to talks with ASEAN on the issue.

But many analysts question Beijing's commitment and say it is likely stalling while it shores up its maritime claims.

China's foreign ministry dismissed Manila's accusations in the land reclamation row, saying last week that "small countries cannot make trouble out of nothing".

Del Rosario has said the Chinese reclamation would impair freedom of navigation in the waters, through which much of the world's trade passes.