Turkey is working with western nations to prepare sanctions against Syria in protest at its violent six-month repression of protesters. Prime Minister Recep Tayyip Erdogan's announcement widens the rift between Ankara and Damascus, formerly close allies. The sanctions, if imposed, would put Turkey more firmly on the side of the United States and leading European powers in opposing the regime of Bashar Al Assad. Mr Erdogan made the announcement after a meeting with Barack Obama, the US president. Both leaders are in New York for the UN General Assembly. "My discussions with the Syrian government have stopped," Mr Erdogan told a news conference late on Tuesday. "We did not want to arrive at this point, but unfortunately the Syrian government has pushed us to such a decision." Mr Erdogan said Turkey would cooperate with Washington on sanctions. US measures include a ban on the import of Syrian oil and the freezing of assets of Syrian government officials. The European Union plans to bring in new sanctions against Syria on Saturday, including a ban on investments in the oil sector and on delivering bank notes and coins made in Europe. "When it comes to what our sanctions may be, we have asked our foreign ministries to work it out," Mr Erdogan said. "They may not be the same as the ones employed against Libya; sanctions vary from country to country. They will be different in the case of Syria." Government officials were cautious in describing the work on measures against Syria. "Turkey is considering possible sanctions," a foreign ministry source said. The official said there "could be a review" of the issue after a visit by Mr Erdogan to refugee camps in the southern Turkish province of Hatay, where thousands of Syrians have found shelter in recent months. No date was given for the visit. Mr Erdogan's statement was the strongest expression yet of Turkish frustration over the unwillingness by the regime in Damascus to stop using violence against protesters. The government of Bashar Al Assad, a close partner of Mr Erdogan's government in recent years, has been trying to crush a popular uprising that began in March, and Mr Al Assad has ignored calls by Turkey and others to implement speedy political reforms. At least 2,700 people have been killed by security forces since protests began, according to the UN. Ankara had long argued against sanctions, saying they could end up hurting Turkey, a nation that shares a land border of almost 900 kilometres and many trade links with Syria. That earlier scepticism makes the turnaround all the more remarkable. "Turkey has been calling for reforms in Syria and has acted like a shield for the Syrians in the West, arguing that Syria should be given more time. But that is changing now," Hasan Kanbolat, the director of the Centre for Middle Eastern Strategic Studies (Orsam), a think tank in Ankara, said yesterday. "Ties are about to snap." The Obama administration confirmed that the president and the Turkish prime minister raised the issue of sanctions against Syria during their meeting. Ben Rhodes, the White House deputy national security adviser, said Mr Obama and Mr Erdogan agreed on the need to increase pressure on the Al Assad regime and agreed to consult on possible further steps that "could include sanctions, political pressure, other measures". Mr Erdogan said Turkey had started preliminary work on sanctions and he would look at the issue more comprehensively after his return to Turkey. "We have no more confidence in the Syrian government," Mr Erdogan said. Ibrahim Kalin, an adviser to Mr Erdogan, said on Twitter the decision by the prime minister to visit the refugee camps in Hatay was crucial, as it meant Mr Al Assad was "finished" for Turkey, because "he is finished for his people". The Turkish prime minister had urged Mr Al Assad in several phone calls in recent months to start political reforms, and he also sent Ahmet Davutoglu, his foreign minister, to Damascus last month. Talks broke down after Mr Davutoglu failed to convince Mr Al Assad to take a new course. Unlike its western partners, Turkey has not yet called on Mr Al Assad to resign, however.