Sweden blocked an effort by other EU states to add two telecoms firms in Syria with commercial links to Swedish firm Ericsson to an EU sanctions list this week, EU diplomats said.

European Union foreign ministers meeting in Brussels on Thursday agreed to add 11 Syrian firms or entities to the sanctions list as part of international efforts to end government violence against pro-democracy protests.

The 26 other EU countries had wanted to add two Syrian telecoms firms to the list, but Sweden threatened to block the entire package if they were included, the diplomats said.

"All the other member states had to compromise," one of the diplomats said. "Sweden argued that the two networks were critical to the functioning of the whole telecoms network."

Swedish Foreign Minister Carl Bildt told Reuters that telephone networks were vital for opponents of the Syrian government to communicate, and called suggestions in Swedish media that Sweden had acted to protect Ericsson's interests "ignorant."

A previous round of EU sanctions targeted Syria's main mobile phone operator, Syriatel, which was supplied by Ericsson, the world's top supplier of mobile phone network infrastructure.

Ericsson spokeswoman Helena Norrman said the South African mobile operator MTN remained a customer in Syria, as did STE, Syria's fixed network firm.

She said Syriatel had been a client until sanctions were introduced in September, at which point current contracts were halted. She said Ericsson had not signed any new orders with the two other firms this year and any deliveries had been under existing deals.

The diplomats said it was very unusual for Sweden, known as a staunch defender of human rights, to block sanctions, or for one member state to act alone to do so.

The decision to remove the two telecoms firms from the sanctions list was taken at working level before it was put to foreign ministers for formal approval, they said.

Bildt said he did not know if Sweden had vetoed any proposals, but there may have been proposals dropped because they were counter-productive.