Washington - The United States on Tuesday closed down Syria's embassy to Washington and ordered its remaining diplomatic staff to leave the country if they were not US citizens.
Washington also notified Damascus that it would no longer be able to operate its two consulates in Troy, Michigan, and Houston, Texas, after the embassy announced last week it would no longer provide any consular services.
US Secretary of State John Kerry said the decision was taken because "the illegitimacy of the Assad regime is so overwhelming".
In the three-year war to topple Syrian President Bashar Assad more than 140 000 people have been killed and the government was "indiscriminately attacking civilians", Kerry told students at a State Department event.
"So we just felt the idea that this embassy is sitting here with representation that we could take seriously is an insult, and we closed it. It's that simple."
The Syrian embassy in the US capital had been operating for some time without an ambassador, who left the US in December 2011, leaving only a few low level staff who had been providing limited consular services.
US special envoy to Syria Daniel Rubinstein insisted however that "despite the differences between our governments, the United States continues to maintain diplomatic relations with the state of Syria as an expression of our longstanding ties with the Syrian people, an interest that will endure long after Bashar Assad leaves power".
A message on the embassy website Tuesday said: "Please Note that Embassy of Syria would not be able to proceed any consular services starting Tuesday 18 March 2014. Thank you for understanding".
Washington also said Syrian diplomats at the embassy, who were not US citizens or permanent residents, were no longer allowed to work in the United States and must leave the country by 31 March.
State Department spokesperson Jen Psaki said this would likely affect about a handful of diplomatic staff and their families.
She confirmed however that the Syrian mission to the United Nations based in New York would continue to operate, as part of US obligations for hosting the UN.
Late last month however, the US restricted the movement of Syria's UN ambassador, Bashar Jaafari, limiting him to a 25-mile radius around New York City.
The Coalition for a Democratic Syria, an association of Syrian-American groups, had accused Jaafari of trying to fuel sectarian divisions among Syrians in his public appearances in the United States.