A Palestinian court on Sunday released on bail a prominent activist arrested after he criticised president Mahmud Abbas's administration.

Issa Amro was detained by Palestinian security forces on Monday in the southern West Bank city of Hebron on accusations including causing "strife", human rights activists said.

His lawyer, Muhannad Karaja, said he has also been accused of creating websites that "aim to undermine the state's security", in violation of a new Palestinian law on cyber crime.

Rights groups have criticised the law, saying it could be used to target critics of the Palestinian leadership.

"We asked for Issa to be released on bail," Karaja told AFP. "The prosecution and the court agreed on this in exchange for a deposit of 1,000 Jordanian dinars ($1,400, 1,200 euros)."

"Issa will appear later before the court regarding this case and all the charges against him," he said.

The hearing was held in secret, with journalists barred from the courtroom. Karaja said he did not know when the next hearing would be held.

Dozens of activists protested outside prosecutors' offices on Sunday over Amro's detention, some with tape over their mouths.

Afer his release, Amro went to the offices of his Youth Against Settlements organisation, where he was warmly greeted by fellow activists and spoke out against the law.

"I hope the president of the state of Palestine will decide today to freeze this law," Amro said.

He spoke of the need for "a space for freedom of speech and freedom of criticism" and accused Palestinian security forces of verbal and "minor" physical abuse against him.

- 'Repressive campaign' -

Amro's Youth Against Settlements is a campaign group in the tense city of Hebron, where Jewish settlers live in heavily guarded enclaves in the centre.

He was detained after post a Facebook post criticising the Palestinian Authority's arrest of a journalist from Hebron.

Palestinian officials have not publicly commented on Amro's detention.

Amnesty International and Human Rights Watch both criticised his arrest.

Amnesty has called it the "latest evidence that the Palestinian authorities are determined to continue with their repressive campaign against free speech."

Separately, Amro is on trial by Israel on a range of charges dating back to 2010.

He has rejected all the charges, saying they are politically motivated and aim to prevent his peaceful resistance to Israel's occupation.

"I have been threatened a dozen times by the Israeli occupation and I have received death threats from settlers, but all of this did not and will not stop me," he said Sunday, wearing a shirt emblazoned with the logo "Palestinians Should Be Free".

"I will continue defending my country against occupation and settlements, and defending the Palestinian national project for all the Palestinian people."