Abdel Aziz Rantissi (search), a hard-liner who rejects all compromise with Israel, was chosen Tuesday as the new Hamas (search) leader, one day after the group's founder was assassinated by Israel.

Rantissi said he emerged from secret elections as the chief of Hamas in the Gaza Strip. Khaled Meshaal (search), a Hamas operative based in Syria, remains the leader of the group's political bureau, the main decision-making body.

Initially Rantissi said he was the new head of the Hamas political bureau, giving the impression he was replacing Mashaal, but Hamas leaders later clarified he was only in charge of Hamas in Gaza.

Rantissi replaces Hamas founder Sheik Ahmed Yassin (search), who was slain in an attack by Israel.

Rantissi told The Associated Press that Hamas would press for more attacks against Israel.

"We will be unified in the trenches of resistance," the 54-year-old pediatrician said. "We will not surrender, we will never surrender to Israeli terror."

Since its creation in 1987, Hamas has been run largely as a collective of senior activists in Gaza and the Arab world, with Yassin in a key role as ideologue, spiritual leader and strategist.

Hamas leaders said that while the killing of Yassin was a blow to morale, it would not hamper the group's operations, including its ability to carry out attacks. Hamas is pledged to Israel's destruction.

"Hamas will continue in the same way Sheik Yassin taught us. Hamas has its infrastructure, its institutions," Ismail Hanieh, a top Yassin aide, said as Hamas leaders formed a reception line at a Gaza City soccer stadium Monday night to greet thousands of mourners.

Hamas is secretive about its organization, though the broad outlines are known.

General policy is set by the political bureau, headed by Meshaal in Damascus, Syria. Other members of the bureau include several Hamas leaders in the Arab world, as well as Rantissi, Hanieh and Mahmoud Zahar in Gaza.

The Hamas military wing, Izzedine al Qassam, plans and carries out attacks on Israelis. It is headed by two shadowy figures, Mohammed Deif and Adnan al-Ghoul, who top Israel's wanted list and have been operating from hiding for years.

It remains unclear how much autonomy the military wing has in deciding on the timing and target of attacks, and to what extent it is directed by the political bureau.

Israel said Yassin personally approved many of the hundreds of Hamas attacks it said killed 377 Israelis and wounded more than 2,000 over the years.

"He (Yassin) preached, advocated and served as source of inspiration and planning of murderous attacks," the Israeli army chief, Lt. Gen. Moshe Yaalon, said Tuesday.

All top Hamas members are pledged to Israel's destruction. However, within the group, there are different views on how to reach the objective. Palestinian analysts said Yassin led the more pragmatic wing of Hamas.

In recent interviews, Yassin said his group is ready to participate in elections after an Israeli withdrawal from the Gaza Strip and stop firing homemade rockets at Israel. "He (Yassin) was a moderating factor," said Ali Jarbawi, a political science professor at the West Bank university of Bir Zeit.

Yassin and Hanieh also kept in close touch with the Palestinian Authority, despite fierce rivalries, to try to work out an arrangement with the Palestinian Authority on how to run Gaza after an Israeli pullback.

Rantissi rejects any compromise with Yasser Arafat's government.

Last summer, he was one of the most vocal opponents to Hamas' decision to halt attacks on Israel temporarily.

He is popular among young Hamas activists, and on Monday delivered Yassin's eulogy.

Rantissi spoke at length, making much of his relationship with Yassin — they once shared an Israeli prison cell for several months.

Referring to Yassin, Rantissi said: "We are the ones who gave their commitment to God and to you, and to continue the holy war in the service of God."