A Taiwanese activist's unusual tree-top protest went into its 11th day Sunday and Pan Han-chiang vowed to continue until a local council drops a controversial development project.

The government of New Taipei City, on the outskirts of the capital, plans to build a swimming pool and an underground parking garage in the grounds of a junior high school in the Panchiao district.

Despite objections from conservationists, some nearby residents and alumni and teachers of the school, a contractor started removing five out of the 32 targeted 40-year-old trees from the campus late last month.

In reaction, activist Pan, 46, climbed one of the trees on March 28 and has refused to come down, with meals and water supplied by his supporters on the ground.

The sit-in has halted preparatory work on the project.

"This is the last method we can use now... the protest will continue indefinitely if the government decides to go ahead with the project," his brother Pan Han-sheng told AFP.

The city government insists that the project, estimated to cost Tw$310 million ($10.4 million), is designed to meet public demand and the trees will be replanted elsewhere.

But opponents question the wisdom of removing mature trees -- many of them unlikely to survive transplantation -- to build the swimming pool and especially the underground parking garage, which they say is unnecessary.

"These trees are part of the collective memory of tens of thousands of students graduating from the school. It is cruel to cast off their memory," said Pan Han-sheng.

He said at least 3,000 people have expressed opposition to the project.