Climate Justice Action and Climate Justice Now want to hold a "people's assembly" outside the centre after marching through the Danish capital's suburbs Wednesday morning, representatives from the two groups told a press conference Tuesday.

The "Reclaim Power" event was to also be attended by a few dozen delegates and participants from the conference, mainly from developing countries.

"We will be both non-violent and confrontational," said Stina Gry, a Danish Climate Justice Action activist.

"We will not let fences and physical barriers stand in our way, and we call upon the police to respect our right to make our voices heard," she added.

Organisers expected "many thousands, maybe 5,000" to attend, said Tadzio Mueller, one of the event's coordinators.

"There is a clear guideline that no one will hurt other human beings. The objective is not breaking windows or anything like that, but to make heard the voices that were excluded from this conference," he told AFP.

The march, which has been authorised by Danish police, was to leave the Taarnby metro station at around 8:00 am (0700 GMT), and plans to reach the Bella centre at around noon.

Demonstrators were to be split up into different groups, including "a blue bloc, a green bloc, a bike bloc and a group from the southern (hemisphere countries)," Gry said.

Danish police, which are authorised to "preventively" detain potential troublemakers, have arrested more than 1,500 protesters since the start of the conference, most of whom were released without being charged.

The show of force was strongly decried by the participating non-governmental organisations.

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