TEL AVIV — Israel is turning up the pressure on the Palestinian Authority to return a captured Israeli soldier, arresting dozens of lawmakers from the ruling Hamas terrorist group in the West Bank as tanks and troops took up positions in Gaza.

Prime Minister Ehud Olmert said the invasion of Gaza, launched Wednesday, was aimed at recovering the abducted Israeli soldier and did not constitute reoccupation.

“The objective is bringing Gilad Shalit home alive, healthy and in one piece,” Olmert said in a speech. “We have no intention of recapturing Gaza. Neither do we intend to stay there.”

In a meeting Wednesday with JTA’s editorial staff in New York, Israeli Consul General Arye Mekel hinted that the operation is intended less to find Shalit — Israel is not believed to know his whereabouts in the crowded coastal strip — than it is to pressure Palestinians to hand him over.

The invasion also aims to deal a blow to Hamas’ terrorist infrastructure and stop the firing of rockets into Israel, Mekel said.

With no sign of life from Shalit, a 19-year-old armored corps corporal captured Sunday in a cross-border raid by Hamas and other Palestinian gunmen, there was fear of a major flare-up in fighting.

On Thursday, Israeli security forces detained dozens of Hamas politicians in the West Bank. Eight members of the Palestinian Authority Cabinet were taken into custody, as well as 20 lawmakers from the terrorist group. At least 30 other Hamas political officials were detained.

Raising the stakes further, Palestinian terrorists killed a West Bank settler abducted earlier in the week. The body of Eliahu Asheri, 18, was found early Thursday in Ramallah following intensive Israeli searches in the area.

Security sources said Asheri, a resident of the Itamar settlement, appeared to have been executed shortly after his abduction Sunday by the Popular Resistance Committees terrorist group.

On Wednesday, Israeli forces took up positions around the defunct Palestinian Authority airport near the southern Gaza town of Rafah, effectively cutting off access to neighboring Egypt.

Security sources had expressed concern that Shalit might have been spirited across the border and on to Lebanon, where Hamas’ armed wing is headquartered.

That was ruled out by Maj. Gen. Yoav Galant, commander of Israeli forces in and around Gaza. On Thursday, however, Palestinian militants blew a hole in the border wall with Egypt, raising the prospect of uncontrolled crossings.

In parallel to the ground operation in Gaza, the Israeli air force struck three bridges in a bid to prevent Shalit’s captors from moving him. Another strike, on Gaza’s main power station, knocked out electricity to many residents.

“To our regret, our response may bring about the suffering of civilians in the Gaza Strip. With that said, our operation is focusing on the terrorist operational infrastructure, to limit the possibility of Shalit being moved,” Gallant said.

P.A. President Mahmoud Abbas, who has been in talks with the Hamas government on defusing the crisis, condemned the Israeli offensive as a “crime against humanity.”

But the lack of serious casualties in the first stage suggested Israel was exercising restraint in hope of pressuring the Palestinians to produce Shalit.

Evidence was mounting that Sunday’s raid, in which two other soldiers were killed and seven wounded, was ordered not by Hamas politicians in Gaza but by the group’s top leader abroad, Khaled Meshaal. Meshaal, based in Syria, was said to be upset at talks between P.A. Prime Minister Ismail Haniyeh, of Hamas, and Abbas’ more moderate Fatah faction on a policy document that could be construed as implicitly recognizing Israel.

Mekel told JTA that Israel was “not interested” in the document, and chided Abbas for negotiating with Hamas rather than dismantling the group’s terrorist infrastructure, as he is obligated to do under the “road map” peace plan.

In any case, Israel says the manifesto, penned by Palestinians in Israeli jails, is not enough to warrant resuming peace talks. But some fear it may help Palestinians lift a Western aid embargo imposed when Hamas took power.

Olmert has hinted that Israel could strike at Meshaal, and Israeli planes on Wednesday buzzed a palace belonging to Syrian President Bashar Assad. For now, however, efforts are focused on rescuing Shalit.

Failure to do so, combined with unabated Palestinian rocket fire from Gaza, would be a major setback to Olmert’s plan to “realign” Israeli borders by removing most West Bank settlements and annexing a few others behind the security fence.

Facing off with right-wing lawmakers in the Knesset on Tuesday, Olmert said he would not be dissuaded from his West Bank plan.