Several protesters spent most of the day occupying John Baird's office while others chanted and drummed in the hallway outside. (CBC)

Police dispersed climate change protesters occupying federal Transport Minister John Baird's constituency office in Ottawa on Thursday night.

Ottawa police moved in shortly before 9:30 p.m. Thursday, ordering eight protesters to leave the office on Carling Avenue and threatening to arrest them if they did not, reported Iain Brannigan, a member of the group.

Protesters initially thought two of them had been arrested and could be charged with trespassing. However, in the end, no arrests or charges were made and they received only a warning.

The protesters, some inside the office and others in the fourth-floor hallway outside, had been there since 11 a.m. They drummed, chanting slogans like "This is our future" and "Pensez à vos enfants, protégez l'environnement" ["Think of your children, protect the environment"], while waving banners that read "Climate leaders wanted" and "Stop mocking climate justice."

Sumeet Tandon, an Ottawa university student taking part in the protest, said it was the fifth in a series of sit-ins targeting high-ranking cabinet ministers across Canada leading up to the international climate change summit that starts Dec. 7 in Copenhagen.

Gas emission cuts urged

"We want them to be climate leaders and not be dead weight in Copenhagen," Tandon said. "We're hoping they commit to strong, binding and real science-based commitments."

He added that the protesters want Canada to commit to slashing its greenhouse gas emissions to 25 per cent below 1990 levels by 2020. "And not the meagre three per cent that they're offering."

Originally, six protesters had been inside the office, with several others outside. They said they were prepared to stay indefinitely.

Four left to go to the washroom around 7 p.m. and were locked out when they returned.

Just before 9:30 p.m., some were briefly let back into the office to retrieve their jackets, Brannigan said. Police arrived at the office moments later.

Baird is the Conservative MP for Ottawa West-Nepean. Environment Minister Jim Prentice's office in Calgary and Finance Minister Jim Flaherty's office in Whitby, Ont., were targeted in similar protests recently. Those ended with occupiers being arrested and charged.

With a file from The Canadian Press