A youth living at the foot of Taal volcano rides an outrigger canoe while the volcano spews ash as seen from Tanauan town in Batangas province, south of Manila, on Monday. Photo: AFP

Philippine authorities were struggling Wednesday to keep thousands of evacuees from returning to homes in areas threatened by a feared massive eruption of Taal volcano.

Some 40,000 people have taken refuge in shelters since the volcano let loose a towering burst of ash and jets of lava on Sunday.

Police subsequently set up no-go zones and mandatory evacuations in at-risk towns around Taal, which is about 65 kilometers south of capital city Manila.

But days later locals are ­losing patience and demanding access, even as the nation's seismological agency warns the volcano could unleash a more powerful eruption at any time.

Soldiers have been deployed at checkpoints in some areas, including Talisay, with police officer Sarah Jane Saballa saying, "It's for the safety of the residents."

People around Taal had to leave at a moment's notice, so many fled with just the clothes on their back.

As the volcano has calmed slightly in the past 24 hours and is spewing less ash, the temptation to return has grown.

Seismologists have noted a string of earthquakes and fissures opening up in roads, indicating magma is still on the move and Taal remains very dangerous.

However, some areas have made concessions, allowing people in for short periods, despite the risks.