French President Emmanuel Macron accused Turkey on Thursday of sending Syrian jihadists to fight in the Nagorno-Karabakh conflict, a move that he said changed the situation. Turkey, a close ally of Muslim Azerbaijan, has denied sending mercenaries to take part in the fighting. “We now have information which indicates that Syrian fighters from jihadist groups have (transited) through Gaziantep (southeastern Turkey) to reach the Nagorno-Karabakh theatre of operations,” Macron told reporters on arrival at an EU summit in Brussels. “It is a very serious new fact, which changes the situation”. Fighting broke out last week in breakaway Nagorno-Karabakh - part of Azerbaijan but run by its mostly ethnic Armenian inhabitants - and has reached its most serious level since a war in the 1990s. Earlier on Thursday, France, Russia and the United States called for an immediate ceasefire. The three countries are co-chairs of the Organization for Security and Co-operation’s (OSCE) Minsk Group, set up in 1992 to mediate a peaceful resolution over the disputed enclave. Macron’s office said in a statement he had discussed the issue as part of efforts to reach a ceasefire with Russian President Vladimir Putin during a telephone call. “They also shared their concern regarding the sending of Syrian mercenaries by Turkey to Nagorno-Karabakh,” it said. Neither Macron or the French presidency provided evidence to support the accusation about the mercenaries and the Kremlin made no mention of the accusation. Macron, who has been in a war of words with Turkish President Tayyep Erdogan for months over issues ranging from Syria to Libya and the Eastern Mediterranean, said on Wednesday Ankara was acting in a “warlike” manner. The Russian foreign ministry said on Wednesday Syrian and Libyan fighters from illegal armed groups were being sent to Nagorno-Karabakh. Russia has a military base in Armenia and considers it to be a strategic ally. France’s population includes about 600,000 people of Armenian origin. Armenia’s ambassador to Moscow said on Monday that Turkey had sent about 4,000 fighters from northern Syria to Azerbaijan and that they were fighting there, an assertion denied by an aide to Azerbaijan’s President Ilham Aliyev and the Turkish government. Two fighters, from Turkish-backed rebel groups in areas of northern Syria under Turkish control, told Reuters on Monday they were deploying to Azerbaijan in coordination with Ankara.