Syria's deputy oil minister resigned on Thursday, becoming the most senior official to join the rebel ranks, as Washington revealed it is mulling non-lethal aid to the insurgency.

Abdo Hussameddin announced his resignation in a video posted by activists on YouTube, saying he was joining the revolt.

Defense Secretary Leon Panetta said Wednesday the United States is looking at delivering radios or other non-lethal aid to Syria's rebel forces but warned of the risks of military action against President Bashar al-Assad's regime without international consensus or a unified opposition.

While outraged at the killing of civilians in Syria, the U.S. government is opposed to taking "unilateral" military action and favors pursuing diplomacy to force Assad to step down, Panetta told the Senate Armed Services Committee.

Tunisia has accepted that Saudi Arabia will probably never hand over ousted leader Zine el Abidine Ben Ali to face trial in his homeland, the new president said in an interview to be broadcast Thursday.

Former president Ben Ali has lived in exile with his wife Leila in Saudi Arabia since January 14, 2011, when he fled Tunisia amid an uprising that sparked a string of regional protests known as the Arab Spring.

The U.N. humanitarian chief briefly visited the battered Homs neighborhood of Baba Amr with a Syrian Red Crescent team on Wednesday, as Washington revealed it is mulling non-lethal aid to the rebels.

Valerie Amos was stopped from going into areas of Homs still held by the opposition, despite receiving assurances from Syrian Foreign Minister Walid Muallem in earlier talks that she could go to any part of the country, her spokeswoman Amanda Pitt told Agence France Presse.

Syria's armed opposition groups cannot defeat President Bashar al-Assad's forces, a think-tank expert said Wednesday.

Toby Dodge, the senior Middle East expert at the International Institute for Strategic Studies (IISS), said the fractured nature of the opposition forces meant they were more of an "irritant" to the regime than a threat.

U.S. President Barack Obama Wednesday held a previously unannounced meeting with Libya's interim Prime Minister Abdul Rahim al-Kib and stressed the need for elections to go ahead in June.

The White House said Obama "applauded the prime minister for his leadership during Libya's democratic transition and his government's efforts to rebuild the country."

Hamas will not be drawn into any conflict between Israel and Iran, a senior official of the Palestinian Islamist movement which rules Gaza said on Wednesday.

"Iran does not need Hamas to respond to Israel in the event of an attack, because it has enormous military capabilities at its disposal, which allow it to act without us," Ahmed Youssef, a counselor to the Hamas foreign ministry, told Agence France Presse.

Foreign Sunni jihadists are fighting alongside Syrian rebels who have taken on President Bashar al-Assad, but their numbers are hard to assess and almost certainly small, insurgents and analysts say.

An Agence France Presse correspondent who met several Syrian rebels over a week in the city of Homs, which was recaptured by regime forces on Thursday, said he sometimes saw them mingling with strangers of the same beliefs.

The United Nations' humanitarian chief Valerie Amos entered the battered Baba Amr rebel district of Homs in central Syria on Wednesday along with a Syrian Red Crescent team, the ICRC said.

"Madame Amos entered with the team of volunteers from the Syrian Red Crescent, which stayed 45 minutes in the district," said a spokesman from the International Committee of the Red Cross.

Vladimir Putin on Wednesday rejected the idea of Russia offering Syrian President Bashar al-Assad asylum as a way of helping put an end to nearly a year of bloodshed in its Soviet-era ally.

"We are not even discussing this question," news agencies quoted Putin as telling Kremlin reporters.