Israelis hold candidate Barghouti
Israeli police have arrested Palestinian presidential candidate Mustafa Barghouti, his aides say.
Mr Barghouti was taken away to the Central Police Station as he was campaigning in East Jerusalem's Old City area, witnesses said.
The arrest comes a day after Israel adopted measures said to be aimed at facilitating Palestinian elections due to take place on 9 January.
These included allowing candidates to campaign within East Jerusalem.
Mr Barghouti was "detained for questioning because he has the right to transit through Jerusalem but not be in Jerusalem itself", a Jerusalem police spokesman said.
East Jerusalem was captured by Israeli forces in 1967. It is considered occupied territory under international law, but Israel claims the whole city as its exclusive capital.
Opinion polls suggest Mr Barghouti, a human rights activist, is running second to interim Palestinian leader Mahmoud Abbas in the race to succeed Yasser Arafat, who died on 11 November