Supreme Leader Ayatollah Ali Khamenei sharply criticised US behaviour towards Iran since its 1979 Islamic revolution and said the United States was "hated in the world" and should stop interfering in other countries' internal affairs.

"They give the slogan of change but in practice no change is seen ... We haven't seen any change," Khamenei said in a televised speech to mark the Iranian New Year.

He was speaking in the northeastern city of Mashhad, a day after Obama offered Iran a "new beginning" of diplomatic engagement between the two old foes.

Khamenei said a change of US "words" was not enough and added: "We will watch and we will judge [the new US administration] ... You change, our behaviour will change."

The conference in the Iranian capital meant to counter an international meeting in the Egyptian Red Sea resort of Sharm el-Sheik on Monday that gave a powerful boost to Hamas' rival, Palestinian President Mahmoud Abbas.

The gathering in Egypt also raised $5.2bn in pledges to rebuild Gaza after Israel's recent offensive but the funds will bypass the coastal strip's Hamas rulers.

Hamas wasn't invited to the Egyptian meeting and is considered a terrorist group by the Unites States, Europe and Israel. Iran, like Hamas, doesn't recognize Israel and is the militant group's chief political and financial backer.

"The conference in Egypt sought to weaken Hamas, promote compromise and treason against the cause of the Palestinian people," said lawmaker Mohammad Reza Mirtajoddini, one of the organizers of the Iranian gathering. "But the Tehran conference speaks of resistance against the Zionist entity that understands only the language of force."

Iran's Supreme Leader Ayatollah Ali Khamenei opened the conference Wednesday calling Israel a "cancerous tumor" and saying "resistance" against the Jewish state was the only way to save Palestinians.

Iran's President Mahmoud Ahmadinejad denounced the meeting in Egypt and was quoted Tuesday by the official IRNA news agency as saying that the "difference between the two conferences is like that between Satan and man."

Hamas' power-man from Gaza, Mahmoud Zahar, attended the Tehran conference, which organizers said focused on how to provide assistance to Palestinians. Other Palestinian militant factions, such as Palestinian Islamic Jihad attended, as well as parliamentary delegations from 30 different countries, including Lebanon, Sudan, Afghanistan, Iraq, Pakistan and Mali.

However, it was not clear if the gathering, which ended today, actually raised any funds for Hamas.

Israel's three-week military offensive against Hamas meant to put a halt to Hamas' years-long rocket fire on southern Israel ended in an informal cease-fire Jan. 18. The campaign killed nearly 1,300 Palestinians and 13 Israelis, and left some 15,000 homes destroyed or damaged in the war.