GAZA CITY, Gaza Strip — Hamas militants holding an Israeli soldier said yesterday they would stick to their tough demands in negotiations over his release, emboldened by the high price Israel is paying in a planned prisoner swap with Hezbollah.

The declaration could complicate Israel’s efforts to bring Corporal Gilad Shalit home after two years in captivity. Israel agreed yesterday to free Samir Kantar, a Lebanese convicted in a grisly 1979 attack, along with other prisoners and bodies of Lebanese fighters, in exchange for the bodies of two Israeli soldiers.

Israel has balked at Hamas’s demands for a large-scale release of Palestinian Arab prisoners, including many convicted in deadly attacks. But the Islamic militants said there was no reason to soften their demands in light of Israel’s swap deal with Hezbollah.

In a radio interview, a Hamas strongman, Mahmoud Zahar, said the militants would work “to release people Israel accused of having blood on their hands like Samir Kantar. We have to take advantage of this to release our prisoners.”

An Israeli government spokesman, Mark Regev, would not comment on Mr. Zahar’s remarks.

Hamas-affiliated militants in the Gaza Strip captured Corporal Shalit two years ago in a cross-border raid that killed two other soldiers.

Weeks later, Hezbollah guerrillas burst across Israel’s northern border, seizing two other Israeli soldiers, Ehud Goldwasser and Eldad Regev, touching off a monthlong war.