The radical Popular Front for the Liberation of Palestine (PFLP) is warning that the arrest of its leader by the Palestinian Authority could lead to a confrontation.
The Popular Front for the Liberation of Palestine has said in a statement the arrest of Ahmed Saadat is a dangerous development.
The PFLP has said the detention of its leader puts the Palestinian Authority in opposition to Palestinian and Islamic factions. The group is calling for Palestinian leader Yasser Arafat to release Mr. Saadat.
Hundreds of supporters of the faction marched in the West Bank and Gaza to protest the arrest.
Palestinian police detained Mr. Saadat in the West Bank town of Ramallah while he was attending a meeting with officials from the Palestinian Authority.
Israel had demanded that Mr. Saadat be arrested in connection with the assassination of cabinet minister Rehavam Zeevi last October. The PFLP claimed responsibility for the killing.
Israeli officials reacted to the arrest with skepticism, saying they want proof Mr. Saadat is being held and will be extradited.
Israeli Foreign Ministry spokesman Ayre Mekel has accused the Palestinian authority of staging detentions in an effort to convince the international community it is fighting terrorism.
"The Palestinians have showed over the last several months that they are using arrests, or so-called arrests, as a revolving door policy. These arrests are not serious and it will take a lot more than a Palestinian press release to convince us or convince anybody else in the world that this terrorist is indeed under arrest," he said.
Israel says it will not lift travel restrictions on Mr. Arafat until Mr. Zeevi's killers are detained. Mr. Arafat has been stranded in his West Bank headquarters since last month when Israel destroyed his helicopters and surrounded Ramallah with tanks.
In continuing violence, the body of a man was found in a car with Israeli license plates near the West Bank town of Jenin. The man was an Arab from East Jerusalem who died in a shooting attack.