NSW Police said a "number of people" on the bridge this morning were detained by security personnel, but three were able to climb it.
"The security on the bridge did respond very quickly but with the volume of people that were there... they prevented quick access".
15 activists have been charged after abseiling off the Sydney Harbour Bridge this morning.
Three activists remained hanging off the bridge on ropes but were removed and arrested by 9.30am.
The protesters were calling for Prime Minister Scott Morrison to declare a climate change emergency.
Thirteen people have been arrested after environmental group Greenpeace called on Prime Minister Scott Morrison to "declare a climate emergency" by protesting on the Sydney Harbour Bridge on Tuesday morning.
They unfurled banners - emblazoned with "100% renewables" and "make coal history" - and bright red flags as they dangled beneath the bridge.
Lane eight of the bridge was briefly closed due to the police operation but soon re-opened.
A group of indigenous Torres Strait islanders lodged a formal complaint against the Australian government at the United Nations on Monday, claiming that their climate inaction violated their basic human rights.
'All 13 protesters have been taken to Surry Hills and Day Street Police Stations to assist with inquiries'. Australia is facing a climate emergency right now.
"Rural and regional Australian families have borne the brunt of climate impacts so far in this country", Greenpeace Australia Pacific chief executive David Ritter said. Our political leaders must listen to those already affected by climate disaster and act.
Police are at the scene directly above the three protestors.
It's Greenpeace's position that eliminating coal is one of the key ways to manage climate change.