Palestinian officials are investigating a suspicious letter addressed to Prime Minister Ismail Haniyeh that allegedly sickened seven people.
They say the people required medical care after opening the letter at Mr. Haniyeh's West Bank offices. Officials say the letter had a Tel Aviv postmark.
Mr. Haniyeh lives in Gaza and is banned by Israel from traveling to the West Bank.
Meanwhile, Palestinian officials say Israel arrested two officials from Mr. Haniyeh's Hamas group on Sunday. One of the men was parliamentary speaker Abdel Aziz Duaik, who Israel describes as a leader of a terrorist group.
Hamas' charter calls for Israel's destruction.
Israel has detained more than 30 Hamas officials since Palestinian militants killed two Israeli soldiers and kidnapped a third in June.
Separately, Palestinian security sources say a Palestinian man was shot dead while driving in the West Bank early Monday.
