A prominent Turkish professor on Thursday began a jail sentence after being convicted of preventing a female student wearing a Muslim headscarf from entering the university where he worked, his lawyer said.

Rennan Pekunlu, a former professor of astrophysics at Ege University, was sentenced to two years in prison in 2012 for violating a headscarf-wearing student's "constitutional right to education" by barring her from entering the faculty.

Turkish President Recep Tayyip Erdogan savaged critics of his remarks that Muslim explorers traveled to the Americas before Columbus as suffering from an "ego complex", reaffirming his belief their purported feat was an historical fact.

"I have been the target of heavy criticism by the Western media," Erdogan said during an address at a meeting of Standing Committee for Economic and Commercial Cooperation of the Organisation of Islamic Cooperation (COMCEC) in Istanbul.

An Ankara court on Wednesday acquitted the only suspect in a case over the alleged poisoning of former president Turgut Ozal, who died in office in 1993, a defense lawyer said.

Retired general Levent Ersoz, 60, has been on trial since October last year accused of attempted murder.

Turkish President Recep Tayyip Erdogan on Wednesday slammed U.S. "impertinence" on the Syrian conflict, exposing the extent of strains between Washington and Ankara days after his key meeting with U.S. Vice President Joe Biden.

Ties between the the U.S. and Turkey have soured in recent months over the reluctance of Turkish leaders to intervene militarily in the U.S.-led campaign against the Islamic State jihadists, who have taken control of swathes of Iraq and Syria. 

The U.N. Security Council will move to allow cross-border deliveries of relief supplies to Syria for another year, the president of the council said Tuesday, as new figures showed more Syrians were in need of aid.

The Council in July agreed in a resolution to allow truckloads of much-needed aid to cross into rebel-held Syrian territory without the consent of the Damascus regime.

At least 500 migrants are believed to be on board a freighter adrift south of the island of Crete, the Greek coastguard said on Tuesday.

"We estimate that there are between 500 and 700 people on board," a coastguard spokeswoman told Agence France Presse.

A Turkish regional governor was accused Monday of inciting hatred towards the country's Jewish community after suggesting a synagogue be turned into a museum as a reprisal for Israel's policies over the al-Aqsa mosque in Jerusalem.

Dursun Ali Sahin, governor of the northwestern province of Edirne, sparked an outcry when he said Friday that the ancient Buyuk Sinagog (the Great Synagogue) built in 1907 under Ottoman Sultan Abdul Hamid should only be used as a museum.

Kurdish fighters gained ground from jihadists of the Islamic State group in fierce battles in the Syrian town of Kobane overnight, a monitoring group said on Monday.

The town on the border with Turkey has become a highly symbolic battleground in the war against IS with the U.S.-led coalition launching near daily air strikes in support of its Kurdish defenders.

U.S. Vice President Joe Biden on Sunday wrapped up a key visit to Turkey without a breakthrough on military cooperation in the Syrian crisis but with officials confident the talks brought their positions closer.

During his three-day trip to Istanbul, Biden held several hours of talks with both Turkish President Recep Tayyip Erdogan and Prime Minister Ahmet Davutoglu on the crises created by the capture by Islamic State (IS) jihadists of swathes of Iraq and Syria.

U.S. Vice President Joe Biden on Saturday met Turkish President Recep Tayyip Erdogan in Istanbul in a bid to ease strains over the Syria crisis and persuade Turkey to step up its support for the coalition against Islamic State (IS) jihadists.

The trip to Istanbul by Biden, the highest ranking U.S. official to visit Turkey since Erdogan was elected president after over a decade as prime minister, comes amid unusual tensions in the traditionally strong relationship between the two NATO allies.