At least one person was killed and four hurt Tuesday in Istanbul when an overpass bridge collapsed onto a busy street, slicing a heavy goods vehicle in two, police said.

Cengiz, a street seller who plies his trade selling bread rings in the center of Istanbul, is usually a fervent supporter of Turkey's newly-elected President Recep Tayyip Erdogan. But on one issue, he begs to differ.

"I support Erdogan. But I must say he made one error and that's to allow the Syrians into our country," he said.

With a youthful and dynamic candidate, Turkey's main Kurdish political force is seeking to broaden its appeal in presidential polls where the votes of the Kurdish minority are set to play a crucial role.

Turkish Prime Minister Recep Tayyip Erdogan on Wednesday faced accusations of racism days before he stands in presidential elections after saying in a television interview that it was ugly to be called an Armenian.

During a live interview on the private NTV channel late Tuesday, Erdogan complained that the opposition was carrying out a smear campaign against him by claiming that he was from another ethnic origin.

Thousands of people on Sunday turned out for a mass rally in support of the Kurdish candidate in Turkey's presidential elections, in a rare large-scale show of Kurdish nationalism in the center of Istanbul.

Some 10,000 people rallied by the shores of the Bosphorus in Kadikoy, the main hub of the Asian side of Istanbul, for the address by Kurdish candidate Selahattin Demirtas.

Three people were killed Sunday and several were injured when a public bus in Istanbul burst into flames after crashing into the side of the road, Turkish television reported.

The bus was reduced to a burnt-out shell after the accident, which happened in the district of Kavacik on the Asian side of Istanbul, pictures broadcast by NTV television showed.

Turkey is to take "drastic measures" to deal with the influx of tens of thousands of Syrian refugees into its biggest city Istanbul, including forcibly sending them to camps in the southeast, the city's top official said Wednesday.

Istanbul governor Huseyin Avni Mutlu said that there were now 67,000 Syrian refugees in the city and legislation would now be adopted that could see them effectively expelled from the city of 15 million to refugee camps closer to Syria.

The extremist Islamic State of Iraq and the Levant has appointed an “emir”, or leader, over Lebanon and has set up a camp to train would-be suicide bombers and send them to Lebanon, a media report said on Sunday.

According to information obtained by LBCI television, security agencies' investigations have revealed that “the ISIL has appointed Abdul Salam al-Ordoni as an emir over Lebanon.”

The trial of more than two dozen anti-government protesters began in Turkey on Thursday with one defendant blasting the charges against them as "ridiculous" and Amnesty International denouncing the process as a "show trial".

Twenty-six members of the Taksim Solidarity umbrella group, including doctors, architects and engineers, face lengthy prison terms for their part in leading the protests a year ago, with the prosecutor calling for 13-year jail terms for the five main suspects.

Turkish police on Sunday fired tear gas and water cannon at hundreds of protesters in Ankara a day after violent clashes on the one-year anniversary of the country's largest anti-government demonstrations in decades.

Police stepped in to disperse around 500 people from Ankara's downtown Kizilay Square who wanted to stage a demonstration at the site where a 26-year-old protester was shot and killed by police the same day last year, an Agence France Presse photographer said.