The officials told the New York Times the CIA officers are helping the allies decide which Syrian opposition fighters across the border will receive arms to fight the Syrian government.
The arms are being funneled mostly across the Turkish border by a network of intermediaries that include Syria's Muslim Brotherhood. They are paid for by Turkey, Saudi Arabia and Qatar, the Times reported Thursday.
A senior U.S. official said the CIA officers have been in southern Turkey for several weeks, in part to keep weapons out of the hands of al-Qaida and other terrorist groups.
The Syrian Network for Human Rights reported a number of extra judicial executions of civilians by military forces Thursday including three in the Damascus suburb of Douma.
Random artillery shelling by the military killed a child in Homs and severely injured a group of children in Dar'aa.
The struggle inside Syria has the potential to intensify in coming months as powerful new weapons are flowing to both the Syrian government and opposition fighters.
Diplomats said both Washington and London might be willing to offer safe passage or clemency to Syrian President Bashar Assad if he relinquishes power.
The possibility -- modeling an Assad exit similar to one that of former Yemeni President Ali Abdullah Saleh in February -- emerged after U.S. President Barack Obama and British Prime Minister David Cameron met individually with Russian President Vladimir Putin at the summit of the Group of 20 leading industrial and developing economies in Los Cabos, Mexico, the diplomats told the British newspapers The Guardian and The Independent.
U.S. and British officials were convinced after the meetings that Putin was not wedded to Assad remaining in power indefinitely, although Moscow is reluctant to say this, the newspapers said.
"Those of us who had bilaterals thought there was just enough out of those meetings to make it worth pursuing the objective of negotiating a transitional process in Syria," a senior British official told The Guardian.
An Assad clemency offer, protecting him from prosecution by the International Criminal Court -- which prosecutes individuals for war crimes, genocide and crimes against humanity -- could involve letting him flee Syria for another country, possibly Russia or Iran, The Independent said.
"It is hard to see a negotiated solution in which one of the participants would be willing voluntarily to go off to the International Criminal Court," a senior British official told The Guardian.
On the basis of the Putin discussions, U.S. Secretary of State Hillary Clinton will ask U.N.-Arab League special envoy Kofi Annan to change the format of his plans for a contact group on Syria, and instead host a conference, using Saleh's removal from Yemen as a model, The Guardian said.
The State Department had no immediate comment.
In Saleh's case, he was granted immunity in February, despite the massacre of civilians during a popular uprising against his regime. Yemeni Vice President Abdu Rabbo Mansour Hadi, to whom Saleh ceded power, is drawing up a new Constitution.
The Annan conference, in Geneva, Switzerland, could be held as early as next week, the sources said.
The talks would focus on the part of Annan's six-point peace plan, which Assad signed, that calls for "a Syrian-led political process," which Western diplomats says would end in Assad's departure.
The meeting would include Syrian regime and opposition leaders, the five permanent U.N. Security Council members and key regional powers such as Turkey and Saudi Arabia.
Moscow has been pressing for Iran to participate, an idea Washington and London reject.
The optimal scenario would be to create a timetable of 18 to 24 months to establish a new Syrian government, without Assad, but perhaps with some current regime members still remaining, along with opposition representatives, The Independent said.
Syrian elections eventually would be held.