Some 47 people were arrested Thursday in London as dozens gathered outside the justice ministry brandishing banners saying "I oppose genocide. I support Palestine Action".

If they are charged and sentenced under UK terrorism laws, they could risk up to six months in prison for holding such banners.

There were demonstrations in about 20 towns and cities on Tuesday with about 142 people being arrested out of 240 demonstrators, the protest organisers Defend Our Juries said.

More than 2,000 people have been arrested since Palestine Action was banned in July as a terrorist group, making it illegal to voice or show any support for them.

The government accuses the group of carrying out acts of vandalism on Israel-linked sites, including an airforce base.

The group was added to a UK blacklist which also includes groups such as the Palestinian militants Hamas and the Lebanese armed organisation Hezbollah.

On Thursday, London police announced that 120 people had been charged for supporting the group after taking part in an August 9 protest in the British capital. So far 254 people have been charged, it added.

The group's co-founder Huda Ammori is due to challenge the ban on Palestine Action during a three-day trial against the interior ministry starting on Tuesday, November 25.

Palestine Action was banned under the UK's Terrorism Act of 2000 following acts of vandalism, including at a Royal Air Force base, which caused an estimated pound7 million ($10 million) in damage.

- Free speech threat -

Critics, including the United Nations and campaign groups such as Amnesty International and Greenpeace, have condemned the ban as legal overreach and a threat to free speech.

Elizabeth, a 54-year-old doctor, told AFP she was taking part in Thursday's protest "to support Palestine and Palestine Action".

"And also to protest against the government, which is turning out to be more of an authoritarian government than a democratic one," she said.

"I'm afraid that there will come a time, very soon, where there won't be any civil liberty."

Six people who are on trial accused of breaking into an Israel-based defence firm's UK site last year and causing more than pound1 million of damage with sledgehammers appeared in a UK court on Monday.

A group of around two dozen protesters, holding banners and Palestinian flags, gathered outside the court on Monday, with their shouts of "Free Palestine" audible inside the courtroom ahead of the start of the trial.

According to Defend Our Juries, six jailed activists linked to Palestine Action have launched a hunger strike calling to be released on bail and demanding the group be de-proscribed.