BeiJing, China - Foul-smelling green algae that has been plaguing China's Olympic sailing venue has been cleared, state media said on Tuesday, after more than one million tonnes of the sludge was removed.

Authorities had set a Tuesday deadline to clean up the algae bloom in Qingdao, drafting 10,000 soldiers and volunteers and hundreds of fishing boats to help with the mammoth task.

After a month of working to remove the algae, which had hit about one third of the venue, two barriers have now been erected to keep any more algae out, the official Xinhua news agency said late on Tuesday.

The barriers are 22 and 20 kilometres (12 and 13 miles) long.

The algae bloom had become an unexpected nightmare for Olympic organisers, disrupting international competitors' training and throwing an embarrassing spotlight on the massive environmental problems in China.

'We will also assign ships to the scene, monitoring the algae,' said Mr Jiang Daming, governor of Shandong province, where the venue is located, about 550 kilometres (340 miles) southeast of Beijing.

'Once algae is found near the barriers, it will be immediately cleared,' he was quoted as saying.

Soldiers had been racing against time to scoop up the algae with shovels, rakes and their bare hands, creating piles of woolly green clumps on the shore.

On Tuesday, 303 athletes from 33 countries practised at the venue, although heavy fog shortened visibility to only 200 metres, Mr Wang Wei said.

Environmentalists say the algae is caused by sewage and agricultural waste.

But government officials have played down links to pollution, saying this year's unusually large bloom is due to heavy rain and hot weather.

Tuesday's report did not mention if the algae - which has a smell comparable to rotting broccoli or cauliflower - had been removed from nearby ports and beaches, where it spread after first being detected in mid-June. -- AFP