President Barack Obama warned Monday that new "tactical" disagreements loomed between Israel and Washington, but vowed to leverage his administration's "creative powers" in the cause of peace.

Obama, who has had a testy relationship with Israeli Prime Minister Benjamin Netanyahu, spoke at length on the stalled peace process at a fundraiser for his 2012 reelection campaign grouping Democratic friends of Israel.

U.N. Secretary General Ban Ki-moon urged Syrian President Bashar Assad on Tuesday to make credible reforms "without delay," after the Syrian leader offered a national dialogue to end months of anti-regime protests.

"He urges the president to carry on these reforms without delay and in a way that is both genuine and credible," Ban's spokesman Martin Nesirky said.

Israel has approved the delivery to the Gaza Strip of materials to build 1,200 homes and 18 schools in U.N.-run projects, a defense official told Agence France Presse on Tuesday.

The decision came shortly before the scheduled departure of an international convoy seeking to breach Israel's naval blockade of Gaza and as Israeli officials argued that there is no humanitarian crisis there.

Wounded Yemeni President Ali Abdullah Saleh is "well" but the date of his return cannot be confirmed, the deputy information minister said on Tuesday, amid conflicting reports on the embattled leader's health.

"We have no confirmation yet" on the date of the return of Saleh, recovering in Riyadh from wounds sustained in an explosion as he prayed at his palace mosque earlier this month, "but we assume he'll be back within the few coming days," Abdo al-Janadi told Agence France Presse.

Palestinian leader Mahmoud Abbas arrived in Ankara Tuesday for talks with Turkish leaders amid disagreements over the formation of a Palestinian unity government, officials said.

Abbas will have a "private program" before talks with Turkish leaders on Thursday and Friday, a Turkish diplomat told Agence France Presse, without giving other details.

The army of Moammar Gadhafi has laid land mines in Libya's Nafusa Mountains to counter rebel attacks there, Human Rights Watch said on Tuesday.

The mountains, which lie to the south of Tripoli, have been the site of clashes between the two sides, as the rebels attempt to edge toward the capital.

Tunisian authorities came under fire Tuesday for their high-speed sentencing in absentia of ousted president Zine El Abidine Ben Ali and his wife to 35 years in jail for embezzling public funds.

The court's quick verdict Monday after only six hours of deliberation on the first day of the landmark trial was dismissed as a "charade" by some Tunisians and a "joke" by a Ben Ali lawyer.

Syrian security forces opened fire on protesters on Tuesday, killing four people, even as President Bashar al-Assad ordered a general amnesty, activists said.

"Two civilians were killed in Homs and six wounded when security forces opened fire on demonstrators calling for freedom," an activist in the central city said.

France stepped up pressure Monday on the United Nations to speak out against Syria's deadly crackdown on protests, but Russia again said it opposed "interference" in the country's internal affairs.

"The U.N. Security Council cannot remain silent for much longer," French Prime Minister Francois Fillon said during a joint press conference in Paris with his Russian counterpart Vladimir Putin.

Gunshots and explosions were heard Tuesday from the Syrian side of Turkey's border with the unrest-hit Arab country, where thousands of fleeing people have massed, an Agence France Presse reporter said.

The shooting appeared to come from a hill overlooking the demarcation line at the frontier, about a kilometer from the Turkish border village of Guvecci, the reporter said.