Surging waters in southern China's swollen Pearl River delta threatened millions of people on Wednesday as authorities raced to finish the evacuation of 110,000 people in the quake-hit southwest.

A deluge of water -- 0.45 metres (1.5 feet) above warning levels -- poured past the Makou monitoring station in the Pearl River delta on Tuesday, the state flood headquarters reported on its website.

The headquarters said the amount of water that sped by the station was the biggest in 50 years and had prompted emergency measures to protect millions of people in the delta, home to China's large export industry.

More rain was forecast for Wednesday, but the downpours over southern China were expected to recede by the weekend, said the state flood headquarters.

Up to 171 people have died and 52 have gone missing in flood-related incidents in China this year, with a majority of the fatalities coming since torrential rains pummelled south China beginning in early June, it said.

According to the civil affairs ministry, 63 people were dead and another 13 missing in nine southern provinces and regions from the June rains, while state media said more than 200 were dead or missing.

Since the rainy season began in late May, rains have deluged large swathes of southern China, bringing more misery to quake-hit Sichuan province, where millions of refugees are living in tents and makeshift shelters.

According to the Beijing News, the evacuation of up to 110,000 quake refugees from dangerous mountainous areas threatened by rain-induced landslides in Aba prefecture was slated to finish Wednesday.

The operation began days ago on the orders of Prime Minister Wen Jiabao, and included up to 70,000 quake refugees in Aba's Wenchuan county, the epicentre of the May 12, 8.0-magnitude earthquake, reports said.

Up to 87,000 people were reported killed or missing after the massive quake, with as many as five million left homeless.

More than 1.66 million people have been evacuated in the areas hardest hit by the rains, with large tracts of farmland under water and economic losses totalling 14.5 billion yuan (2.1 billion US dollars), the civil affairs ministry said Tuesday.

Officials also warned that the north could fall victim to the weather, and the government has urged the strengthening of dykes and reservoirs along the Yellow River, known as the "cradle of Chinese civilisation" and home to millions of urban dwellers and farmers.

In the south in Guangdong and neighbouring Guangxi province, the rains have either swamped hundreds of roads or left them cut off by landslides.

Thousands of transport trucks have been stranded in both provinces, cutting off food supplies to urban centres and fuelling price rises, reports said.

The National Development and Reform Commission, China's economic planner, issued orders Wednesday to curb price gouging in the flood-hit areas. Vegetable prices reportedly rose by 70 percent in some parts of Guangdong last weekend.