An Israeli military court on Tuesday ordered the Hamas speaker of the Palestinian parliament be held in administrative detention for six months, his office told AFP.
The order against Aziz Dweik, who was detained by Israeli troops on Thursday last week, came as Israeli officials arrested another Hamas lawmaker, the fifth senior member of the Palestinian movement to be held in the past five days.
"The court of the Zionist military occupation at Ofer ordered that Aziz Dweik, speaker of the Palestinian Legislative Council, be placed in administrative detention for six months," a source in his office told AFP.
The decision came after a series of arrests in east Jerusalem and the West Bank.
A day after Dweik's arrest, troops detained Hamas MP Khaled Tafesh at his home in a village east of Bethlehem.
And on Monday, police arrested another two senior Hamas officials at the east Jerusalem headquarters of the International Committee of the Red Cross (ICRC).
Later that night, soldiers arrested Hamas lawmaker Abdul Jaber Fuqaha in his home in Ramallah, Hamas sources and the military said.
The Jerusalem arrests saw police detaining Khaled Abu Arafeh, a former minister for Jerusalem affairs, and Hamas MP Mohammed Totah, who were snatched from inside the ICRC offices where they had been taking refuge since July 1, 2010.
Two other Hamas MPs who took refuge with them at the same time have already been arrested and deported to the West Bank.
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All four had their Jerusalem ID cards revoked by Israel, and were staying in the compound in a bid to avoid being detained.
On Tuesday, Totah and Abu Arafeh appeared at Jerusalem magistrate's court where a judge extended their remand in custody until Sunday.
"There is a need to extend their detention until 29/1/12 at midday," the court order said.
The arrests sparked an angry response from Hamas, which lashed out at "the continuation of a fierce campaign being waged against us by the occupation."
It also drew fire from the Palestinian cabinet which accused Israel of waging a campaign against the parliament, or Palestinian Legislative Council (PLC).
"The cabinet condemns the continued Israeli detention campaign against the Legislative Council members, and demands the Israeli government immediately release all lawmakers," a cabinet statement said.
"Those detentions are in contravention of international law and signed agreements."
And Hanan Ashrawi, a prominent member of the Palestine Liberation Organisation, accused Israel of using a "calculated means of coercion and power politics to interfere in Palestinian domestic affairs and to undermine democratic institutions in Palestine."
The arrests come as Hamas and the rival Fatah movement of president Mahmud Abbas try to implement a reconciliation deal, which could be jeopardised by the continued arrests of members of the Islamist group.
Hamas has 74 MPs in the 132-member PLC, of which 24 are currently being held by Israel. Most of them have been arrested in the past 15 months.
Parliamentary sources say Israel is also holding another three Palestinian MPs -- two from the ruling Fatah party of president Mahmud Abbas, and one from the leftwing Popular Front for the Liberation of Palestine.