Israel is considering expelling Hamas leaders from the West Bank to Gaza as part of its response to the kidnapping of three teenagers, which it has blamed on the Islamist group.

The deliberations come as Israel continued to round up members of Hamas in six West Bank towns for the third night running, including senior Palestinian lawmakers, in one of the biggest waves of arrests in recent years.

Thousands of Israeli troops and police have joined in the hunt for the three seminary students – Gil-ad Sha'er and US-Israeli national Naftali Frankel, both 16, and Eyal Yifrach, 19 – who disappeared while hitchhiking home from a yeshiva, or religious school, on the West Bank.

The kidnapping has gripped Israel, with constant news coverage and prayer vigils since news broke of the youths' disappearance on Thursday.

The Israeli prime minister, Binyamin Netanyahu, spoke on the phone with the Palestinian president, Mahmoud Abbas, on Monday for the first time in almost a year. Netanyahu demanded that Abbas help with the hunt for the missing youths and arrest the kidnappers.

Breaking his silence on the kidnapping and the Israeli clampdown, Abbas issued a statement condemning "the series of events over the last week, beginning with the kidnapping of the three Israeli teens and ending with a series of Israeli violations".

Although Israel has insisted Hamas was responsible, it has yet to provide any hard evidence linking the kidnapping to the group. In ominous remarks, the chief of Israel's armed forces, Lieutenant General Benny Gantz, said the military was preparing to expand its operations.

Gantz said: "We have a goal, and that is to find these three boys and bring them home, and to hit Hamas as hard as possible – and that is what we are going to do. We are on our way toward a significant campaign. We will get our plans in order."

An Israeli government official, who spoke on condition of anonymity to Reuters, said Israel was looking to capitalise on the search by enforcing a wider clampdown on Hamas in the West Bank.

In an interview, the aunt of Naftali Frankel, Ittael, expressed the family's gratitude for the nationwide support and for the government's efforts to find him. "We are of course very, very worried," she added. "We really, really want to see him home fast."

Israeli forces have arrested more than 150 Palestinians, most of them from Hamas, over the past four days. The detainees included 10 Hamas legislators – one-third of the Hamas representatives from the West Bank in the long-defunct Palestinian parliament.

Among those arrested in Hebron – which has been the focus of the Israeli operation – was the speaker of the Palestinian legislative council and Hamas member Aziz Dweik, who was arrested in the early hours of Monday morning.

"They came for him at 2.30 in the morning," his son, Anas, told the Guardian at the family's home. "He was expecting it, so he had his medicine ready in a bag. I don't think it's fair. My father has not been arrested for anything he did. He has nothing to do with finding these young men. He is a political figure.

"[After the kidnapping] my father said he thought it was not helpful and would have a dramatic and negative influence on the Palestinian unity government [which is backed by Hamas]."

Elsewhere in Hebron, the city's mayor, Daoud Zatari, who on Monday visited the homes of families raided overnight, accused Israel of imposing "collective punishment" on his city of 750,000 in largely sealing it off. He added that Hebron's residents were afraid of further escalation.

The three Jewish students went missing late on Thursday while hitchhiking at a West Bank bus stop near the Palestinian city of Hebron. They were en route home, two to West Bank settlements and the third, an American citizen, to a small community in Israel. Large numbers of Israeli troops have been involved in a massive search since then, going from house to house in some areas.

Abbas's aides have rejected Netanyahu's contention that the Palestinian self-rule government was ultimately responsible, saying that Israel was in overall control of the West Bank.

The alleged kidnapping took place at a road junction that is under direct Israeli control and is commonly used by soldiers and Jewish settlers.