Palestinian gunmen have stormed election offices in the Gaza town of Khan Younis ahead of the January parliamentary poll, witnesses say.
Militants associated with the ruling Fatah party are also said to have surrounded a poll office in Rafah.
Palestinian leader Mahmoud Abbas has been expected to try to end a damaging split within the party by presenting a unified list of candidates.
He has also appealed to militants to halt rocket attacks on Israel.
Islamic Jihad is reported to have rejected his call at a meeting of armed groups in Gaza, and blamed Israel for a recent escalation in violence.
There were more Israeli air strikes against targets in Gaza early on Wednesday morning, but there are no reports of casualties.
The Israeli army said the aircraft had attacked access roads used by militants to fire rockets at Israeli targets.
Armed groups have been able to fire missiles deeper into Israel since it withdrew from Gaza in September.
Chaos fears
Fatah has been in disarray since a group of younger members led by jailed West Bank intifada leader Marwan Barghouti broke away.
The rival faction submitted its own list of candidates for the poll two weeks ago.
Tensions turned to violence earlier this month when three people were injured in clashes at the party headquarters in Gaza.
Correspondents say the so-called old and new guard have disagreed for some time over the direction the party should take.
There are fears that the infighting could throw Palestinian politics into chaos and could even threaten the election process itself, they say.
Fatah is expected to face a strong challenge in January's poll from the militant Islamist group, Hamas.
The 25 January poll will be only the second since the establishment of the Palestinian Authority in 1995.
