Israeli troops have detained another senior Palestinian parliament figure, Mahmoud al-Ramahi.
Mahmoud al-Ramahi's wife spoke to the press after he was seized
The family of the parliamentary secretary-general said he was detained after troops surrounded his house near the West Bank town of Ramallah.
This comes a day after the army detained Palestinian deputy prime minister Nasser al-Shaer.
Both are members of the Islamic militant movement Hamas, which won parliamentary elections this year.
Mr Ramahi, the fourth-ranking official in the Palestinian legislature, was detained at his home in El Bireh, a town near Ramallah.
Troops, together with officers of the Shin Bet internal security service, surrounded his house and took him away, an army spokesman said.
Mr Shaer was seized in an early morning raid in the West Bank
Four other ministers and a number of top Hamas officials are being held by Israel following the capture of one of its soldiers by militants in Gaza in June.
Palestinian Prime Minister Ismail Haniya has appealed to the international community for help to secure the release of his deputy Mr Shaer, who was also seized from Ramallah.
The Israeli army said it had detained him because he was a member of a "terrorist organisation".
Israeli troops shot dead a Palestinian and wounded three near Nablus in the north of the West Bank on Sunday, Israeli and Palestinian sources said.
Mr Haniya, a member of Hamas, said the arrest was part of an Israeli attempt to undermine the Palestinian political system
Mr Shaer's wife said her husband had been in hiding since Israel began its crackdown, which has largely focused on the Gaza Strip, Hamas's stronghold.
But politicians from the Islamist movement - which does not recognise Israel - have also been detained in the West Bank.
Israel's position is that Hamas is a terrorist organisation and its leaders are therefore "targets for arrest".