Australian special forces troops are on standby to assist with the rescue of more than 200 schoolgirls kidnapped in Nigeria, the Federal Government has confirmed.

The schoolgirls were kidnapped by Al Qaeda-linked Muslim extremist group Boko Haram in April, sparking international outrage and prompting the campaign "Bring Back Our Girls".

Overnight Nigeria banned the protests in the country's capital Abuja, citing security reasons, but protest organisers have questioned whether a political motive is behind the ban.

Britain and the US have offered help to the Nigerian government.

Foreign Minister Julie Bishop has told Sky News that Australia has offered to lend its support but Nigeria is yet to respond.

"Australian troops, the SAS are always on standby for contingencies," she said.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 3 minutes 56 seconds 3 m 56 s Australia confirms offer to send SAS to Nigeria Download 1.8 MB

"We have made an offer to the Nigerian government to provide whatever support they need to release the girls. We've made a specific offer to our UK and US allies ... that we are ready to assist in whatever way we can.

"We have not had a response from the Nigerian government. They've thanked us for our willingness to be involved in trying to rescue the girls but we haven't had any specific acceptance of the offers that we've made."

Greens demand more details of Nigerian mission

Greens leader Christine Milne is calling on the Government to provide more details before Australia gets involved.

What is Boko Haram? Boko Haram, which means "Western education is sinful", is loosely modelled on the Taliban movement in Afghanistan.

Boko Haram, which means "Western education is sinful", is loosely modelled on the Taliban movement in Afghanistan. The group considers all who do not follow its strict ideology as infidels, whether they are Christian or Muslim.

The group considers all who do not follow its strict ideology as infidels, whether they are Christian or Muslim. It demands the adoption of Sharia law in all of Nigeria. Read more

"The Greens want to see the schoolgirls in Nigeria rescued," she said.

"It is shocking to think all those young women have been dragged away and we don't know the circumstances in which they find themselves but I think the PM needs to inform Australia fully as to what Australia would be getting into if we sent troops into Africa.

"Is this just about rescuing the schoolgirls or is this about joining a coalition to take on another terrorist war in sub-Saharan Africa?

"Australians deserve a full explanation of what the PM's thinking is before we can make any comment about it but I would be remembering that we went into Afghanistan ... and look where we ended up."

West African leaders met in Paris in May, vowing to wage "total war" on Boko Haram, saying the group had become a regional Al Qaeda that threatened them all.

The US, Britain, France and Israel are providing varying levels of support to Nigeria's military to help find the girls. French fighter jets based in the Chadian capital N'Djamena are being used for reconnaissance missions.

The European Union on Monday announced sanctions against Boko Haram. These include an arms embargo, asset freeze and travel ban on members and supporters.

This follows a decision by the United Nations to designate the group as a terrorist movement two weeks ago.

ABC/wires