Muhammad al-Hindi, the Gaza leader of Islamic Jihad, said on Thursday the group had decided not to field any candidate in the 9 January election to replace Yasir Arafat and not to support any independent candidate either.
Al-Hindi urged his followers and Palestinians in general not to participate in the poll because it cannot be truly free.
"The Palestinian people who are living under occupation want to have a real election, a free and fair election in a free, liberated land. We cannot say the upcoming presidential election is like this," he said.
The refusal of Islamic Jihad to back the election came a day after Hamas announced it would not field a candidate for the election. However, it left open the possibility of supporting an independent candidate.
Shereen Abu Aqla, Aljazeera's correspondent in Palestine reporting from Ram Allah, said another group, the Popular Front for the Liberation of Palestine (PLFP), has also announced it will not run in the elections, but that it has not called on its members to boycott the poll.
Mahmud Abbas is the Fatah
candidate for president
The groups which have announced their participation so far are: the Fatah movement with Mahmud Abbas its candidate; the Palestinian People's Party with Bassam al-Salhi as its candidate; and the Democratic Front for the Liberation of Palestine (DFLP).
The more the number of groups that participate, the greater the legitimacy of the election, Abu Aqla said.
Also on Thursday, the central election committee said at a news conference that 71% of Palestinians had registered to participate in the election.