Minbar Ansar Deen and Boko Haram face UK membership ban
Support for two extremist groups - Minbar Ansar Deen and Boko Haram - is to be made a criminal offence in the UK.
Home Secretary Theresa May has asked for the two radical Islamist organisations to be banned under terrorism laws.
If approved by Parliament, both will be banned from operating in the UK from Friday, the Home Office said.
Minbar Ansar Deen is based in the UK, while Boko Haram operates from Nigeria.
Minbar Ansar Deen - also known as Ansar al-Sharia UK - promotes terrorism by distributing content through a forum on its website, which encourages individuals to travel overseas to engage in extremist activity, specifically fighting, according to the Home Office.
Boko Haram is a militant Islamist group based in Nigeria led by the country's most wanted man, Abubakar Shekau. Its name means "Western education is forbidden" and it has waged an insurgency for more than a decade.
If the two groups are banned, it will be illegal to support or become a member of either group, to arrange meetings or wear clothing in support of them.
Offenders could face fines of up to £5,000 or up to 10 years in prison.
The Home Office has not yet offered further information on why it is pursuing the ban of both groups.
Raffaello Pantucci, senior research fellow at the RUSI think tank, said the move indicated that the government sees them as a "potential threat".
Banning the groups would give the police powers to tackle their support networks.
The UK-based Minbar Ansar Deen's website has links to Abu Nusaybah, who was arrested after appearing on the BBC's Newsnight programme talking about Michael Adebolajo, one of the suspects in the murder of soldier Lee Rigby in Woolwich.
Mr Pantucci said: "It is impossible to say that this constitutes 'a link,' but looking at the group's website they certainly seem to come from the same ideological constellation."
The activities of the Nigerian-based Boko Haram are usually confined to poor, Muslim parts of northern and central Nigeria.
Historically there is little evidence of Boko Haram targeting the UK, Mr Pantucci said.
"Britain's Nigerian community is 90% Christian," said Mr Pantucci, adding that Nigerian terror suspects in the UK were "usually Muslim converts".
However, earlier this year Boko Haram kidnapped a French family in Cameroon. A Nigerian government report revealed the group was paid more than £2m before releasing its hostages.
The Home Office's move to ban the group could indicate that it is becoming more international, "or leaning in that direction", Mr Pantucci said.
Theresa May flagged up Boko Haram, among other extremist groups, in a speech on terrorism in July 2011.
She said: "Increasingly, the threat to Britain comes not just from al-Qaeda's core leadership itself, but from these so-called al-Qaeda's affiliates in places like Yemen and North Africa... and from associated groups like al-Shabab in Somalia and Boko Haram in northern Nigeria."
A Home Office spokesman said: "The government is determined to work with the international community to tackle terrorism and take the steps necessary to keep the UK public safe.
"Proscription of these groups sends a clear message that we condemn their activities."
There are 49 international terror organisations proscribed under the Terrorism Act 2000, including al-Qaeda, al-Shabab and Islam4UK.
The latter, previously led by the radical Islamist preacher Anjem Choudary, was banned in 2010.
In Northern Ireland, 14 organisations were proscribed under previous legislation.