Syria’s top diplomat in the United Kingdom has defected and left his post at the Syrian embassy in London, the British foreign office said Monday. The defection of Syria’s UK Chargé d’Affaires, Khaled al-Ayoubi, is the fourth by a Syrian diplomat this month, and comes as talks are underway on a transition from Bashar al-Assad’s rule.

“Mr. al-Ayoubi has told us that he is no longer willing to represent a regime that has committed such violent and oppressive acts against its own people, and is therefore unable to continue in his position,” a British foreign office spokesman said in a statement Monday.

His departure is “another blow to the Assad regime,”  that “illustrates the revulsion and despair the regime’s actions are provoking amongst Syrians from all walks of life,” the spokesman said.

The UK-based diplomat’s defection follows those of three other Syrian ambassadors this month, including Syria’s ambassador to Iraq Nawaf al-Fares and Syria’s ambassadors to the UAE and Cyprus, a married couple, last week.

Various Syrian opposition representatives have been involved in transition planning talks  taking place in Cairo, under the auspices of the Arab League.

The United States is meantime expanding its assistance to the Syrian opposition, including non-lethal support to the armed Syrian resistance.

Among the new measures, the U.S. Treasury Department last week authorized the Syrian Support Group to provide financial and logistical assistance to the Free Syrian Army, Al Monitor reported last week. The authorization, contained in a letter from Treasury’s Office of Foreign Assets Control (OFAC) and signed July 23, came as the Free Syrian Army military command issued a “Proclamation of Principles” pledging support for multi-ethnic pluralism and democracy.

US officials have stressed the need for Syria’s opposition to demonstrate such ethnic inclusivity, in order to encourage more defections and to avoid a sectarian bloodbath.  “The future will include all Syrians of all backgrounds,” US Ambassador to Syria Robert Ford said in a statement posted to the embassy’s website July 27.

The United States is also urging Syrian rebels and opposition groups to avoid seeking an Iraq-style disbanding of Syria’s army, the Washington Post reported.

However, Syria’s rebels don’t support one figure reportedly eyed as a potential Syrian unity figure who could hold the army together, Brig. Gen. Manaf Tlas, a close family friend of Assad who defected this month.

Tlas’s “road map is slowly taking shape,” Sabah’s Erdal Safak reported in a piece translated and published by Al Monitor Monday. “Never mind that a part of the opposition says, ‘There is no place for Baath officials or generals in the new era.’  Syria’s friends, definitely the US, see the Syrian army as the sole guarantor of integrity and stability of the country.”

(Members of a Syrian refugee family, who fled the violence in Syria, are seen at a garden in Port Said Square in Algiers July 30, 2012. More than 12,000 Syrians fleeing the violence in their home country have sought refuge in Algeria, a source close to the Interior Ministry said on Sunday. REUTERS/Louafi Larbi.)