(BBC NEWS) Hamas says it has released the top representative of Palestinian Authority President Mahmoud Abbas’s Fatah party in the Gaza Strip.
Zakaria Agha was held for four days after being seized by Hamas gunmen.
He was detained as part of a wave of arrests of Fatah supporters after a beachside bombing killed five Hamas militants and a young girl.
Fatah denied involvement in the attack and carried out its own series of arrests in the West Bank.
“We have released Zakaria Agha as a sign of goodwill and in response to Arab and Palestinian efforts,” Hamas spokesman Taher Nunu told the AFP news agency.
Mr Agha and fellow senior Fatah official Ibrahim Abu Naja were among those arrested in the Hamas crackdown following the coastal bombing.
Both men had been appointed by Mr Abbas to run Fatah in Gaza after Hamas took control in Gaza in June 2007.
Mr Abu Naja and other Fatah officials are believed still to be in custody.
Violence erupted over the weekend when Hamas fighters clashed with a pro-Fatah clan in Gaza City.
Fatah supporters were held by Israel after fleeing from Gaza
Nearly a dozen people were killed and scores wounded in the worst internal feuding since the militant Hamas faction gained power in Gaza.
In the wake of the fighting about 200 Fatah men fled from Gaza into Israel. About 35 were returned to Gaza, where some were detained by Hamas.
Mr Abbas had requested the men be returned to Gaza, to keep a Fatah presence there.
However, the Israeli army later halted the transfer of the men after learning of their arrests and receiving information that “their lives were in danger”.
Instead, about 90 were sent by bus to the town of Jericho on the West Bank, which is controlled by the Fatah-run Palestinian Authority.
They were to be housed in the Palestinian National Security headquarters there, Palestinian officials said.
The remainder of the Fatah supporters were either in hospital in Israel or being questioned by Israeli security forces, the officials said.