The warning came as Turkey voiced backing for a UN resolution slamming Syria’s deadly crackdown on protesters, as a renegade Syrian colonel called for a united front to topple Assad. But Russia said it will not support the draft resolution.

Turkish Prime Minister Tayyip Erdogan, whose country has imposed an arms embargo on Syria, also said he would set out Ankara’s plans for further sanctions after he visits a Syrian refugee camp inside Turkey in the coming days.

Global rights watchdog Amnesty International earlier said Syrian pro-democracy activists had been harassed in eight countries. France confirmed it had launched an investigation after thugs attacked a protest in Paris.

A foreign ministry spokesman said arrests had been made and extra police protection assigned to Syrian opposition protests after the August 26 attack.

“We would not tolerate a foreign state organizing acts of violence or intimidation on our territory, and we have made this known in the clearest possible terms to Syria’s ambassador in Paris,” Bernard Valero said.

“The right to protest freely and peacefully in safety is fully guaranteed by the French constitution, and it is also obvious that France supports the Syrian people’s hopes for freedom,” he said.

Also Tuesday, German Foreign Minister Guido Westerwelle urged UN Security Council members to find a “unified answer” to the crackdown in Syria, warning inaction would weaken the UN’s authority.

“We need to find a united, unified common answer to this repression in Syria which we cannot accept,” Westerwelle said in The Hague after talks with his Dutch counterpart Uri Rosenthal.

According to the French daily Le Monde, a small group of Syrian protesters that gathers regularly in a square in central Paris has been insulted, filmed and on at least one occasion violently attacked by thugs.

Valero confirmed that there had been arrests after one such incident on August 26, but denied a report in the Le Monde that suggested that two of the suspects were carrying Syrian diplomatic papers.

In Sweden, meanwhile, Foreign Minister Carl Bildt warned that: “If there are diplomats who engage in activities in this country that are not compatible with their diplomatic status they are not welcome in Sweden.”

Amnesty International earlier said it had documented cases of attacks and intimidation against 30 activists in eight countries: Britain, Canada, Chile, France, Germany, Spain, Sweden and the US.

It urged countries hosting Syrians, like France and Sweden which have become hubs of opposition activity, to “take stronger action against Syrian embassies accused of orchestrating this kind of harassment and intimidation.”

Amnesty’s Syria researcher Neil Sammonds said Syrians living abroad are becoming increasingly vocal in their support of the growing protest movement back home that has been demanding Assad step down.

“In response the regime appears to have waged a systematic - sometimes violent - campaign to intimidate Syrians overseas into silence,” he said.

Amnesty said protesters outside Syrian embassies are initially filmed or photographed by officials then subjected to harassment, including phone calls, e-mails and Facebook messages warning them to stop.

Some activists say they were directly threatened by embassy officials.

Naima Darwish, who set up a Facebook page to call for protests outside the Syrian embassy in Santiago, Chile, told the rights group she was contacted directly by a senior official who asked to meet her in person.

“He told me that I should not to do such things,” she told Amnesty.

“He said I would lose the right to return to Syria if I continued.”

A number of Syrians said their families back home were targeted by security forces, apparently to deter them from their activities overseas.

After Malek Jandali, a 38-year-old pianist, performed at a demonstration in front of the White House in July, his mother and father, aged 66 and 73, were attacked in their home in the central city of Homs and have since fled Syria.

“We look to host governments to act on credible allegations of abuses,” said Sammonds, adding many dissidents were often “too scared of what could happen to them to make formal complaints with the police.”

The Russian Foreign Ministry, meanwhile, announced that Moscow would not support the European-drafted UN resolution on Syria, calling the draft “unacceptable.”

Deputy Foreign Minister Gennady Gatilov said Russia refused to back the text because it opened the door for punitive sanctions against Syria.

In Paris, French Foreign Minister Alain Juppe said a compromise reached earlier on a resolution had now broken down, with Moscow vowing to deploy its veto.

Gatilov said Moscow also opposes the draft resolution because it fails to include a clause calling on powers not to become involved in internal Syrian affairs and calling for a dialogue between Assad and demonstrators.

Juppe said one thing Russia wanted added, which France categorically refused, was to have the regime and rebels condemned equally in the resolution.

“There is a specific point that is unacceptable and I have instructed my UN ambassador on this and that is that we put the regime and the rebels on the same level,” Juppe said.

France has been one of the strongest voices pushing for a UN resolution to stop the bloodshed in Syria.