The prices of vegetables and fish are going up across the board at wet markets in Singapore, with some vegetables costing about twice as much as they were just weeks ago.

The Straits Times visited five wet markets yesterday and vendors said poor weather conditions in Malaysia have caused a shortage of supplies as farms are flooded, resulting in poor crop output.

Transport is also an issue because roads are closed due to the severe flooding.

Mr Alex Zhou, 35, who runs a vegetable stall at the wet market in Pasir Ris Drive 6, said: "The constant rain in Malaysia has made it hard to transport goods, and we've lost a lot of supply due to the poor weather. Green leafy vegetables like spinach are more affected because they spoil easily in water."

A vegetable stallholder at Geylang Serai Market, who wanted to be known only as Madam Rashidah, 45, and who runs the business with her husband, said: "I had to get vegetables from Thailand and Vietnam, which are flown in. This method is more expensive, causing my prices to go up as well."

Severe flooding in Malaysia over the past few weeks has resulted in tens of thousands of people being evacuated from their homes. Over 48,000 in six states were sheltering in 400 relief centres last Friday.

At the Pasir Ris and Ghim Moh markets, prices of tomatoes have almost doubled, from about $1 to $2 per kilogram to about $3 per kilogram.

A market vendor at Tekka Market said his cost price for tomatoes has more than doubled from $12 per 10kg to $28, while a vendor in Pasir Ris said his supplies now cost $32 per 10kg, up from about $10.

Mr Jerry Tan, vice-secretary of the Singapore Fruits & Vegetables Importers & Exporters Association, noted that prices usually tick upwards towards the end of the year because of the monsoon season, but the past few months have been exceptional.

"Usually, some areas in Cameron Highlands that still get some sun will be able to supply tomatoes," he said. "But this year, the entire area has been raining for the past few weeks. When this happens, the tomatoes cannot ripen and the supply will be affected."

Prices of tomatoes from Malaysia had jumped by about 150 per cent to 200 per cent compared with prices the past week, he said.

"We've never seen such a drastic increase in such a short time before. But suppliers are trying to get their stocks from Thailand and Vietnam, so prices should start to drop and will stabilise soon."

Prices for seafood such as fish and prawns have also crept up.

Mr Goh Thiam Chwee, president of the Singapore Fish Merchants' General Association, said prices of popular items like Chinese pomfret and red snapper, have jumped by about 20 per cent, and this may possibly increase to 30 per cent as Chinese New Year approaches.

"Every year, the prices will rise towards the monsoon season because of the fluctuating sea conditions. But seafood is not so badly affected because we also get our supplies from other countries."