Beach workers and volunteers have cleaned more than 240 tonnes of green algae from the coastline of Qingdao, a port city in Shandong Province, four weeks after the algae bloom began.

More green algae, or enteromorpha prolifera, was washed ashore Monday, leaving a green "carpet" about 400 meters long and 30 meters wide on the beach near downtown Qingdao.

About 40 middle school students joined beach workers to remove the algae Monday, the first day of their summer holidays.

A beach worker said he had been clearing the algae for a week.

Li Li, a preschooler from Handan, an inland city in the northern Hebei Province, said he didn't mind the algae on the beach. "I like the green 'grass.' It feels so soft."

However, most people view the algae as a nuisance.

"It has a disgusting smell and ruins our holiday. Now it's impossible to swim in the sea," said a woman surnamed Yang from the northern Inner Mongolia Autonomous Region.

Though the green algae is not poisonous, it can consume large amounts of oxygen that can threaten marine life. Also, rotten algae emits a foul smell that can hinder tourism along the affected coastline.

The green algae was detected in late May in sea off Yancheng City in east China's Jiangsu Province. It spread to Qingdao on June 9 and covered 43 square km of seawater.

Qingdao's maritime authorities have since launched a clean-up campaign that involved maritime workers and fishermen.

Green algae emerged in the Yellow Sea in 2007. Local residents and soldiers removed tens of thousands of tonnes of it in 2008 before the sailing events of the Olympics in Qingdao.