Turkey’s government is now allowing the insurgent Free Syrian Army to operate from bases inside the Turkish border and is housing more than 35,000 Syrian civilians who have sought refuge from the conflict. The Turks also have sent antiaircraft batteries to the border in response to the June 22 downing of a Turkish military plane by Syrian gunners. On Monday, Turkey’s Defense Ministry said it scrambled warplanes from its Incirlik air base in southern Turkey when three Syrian military helicopters were seen approaching the border.

The number of ranking officers in the Syrian military who are defecting and seeking sanctuary in neighboring countries, mostly Turkey, appears to have increased in the past few weeks. On June 24, a Syrian general, two colonels and major and a lieutenant were among 33 soldiers who fled Syria. A few days earlier a Syrian Air Force pilot, who was both a colonel and squadron commander, defected in a commandeered MIG to Jordan, and Syrian rebels reported that eight Syrian pilots had fled to Jordan overland.

News of the latest batch of defectors came as members of Syria’s fractious opposition movement convened a meeting in Cairo in attempts to devise a unified strategy for pressuring Mr. Assad to step down as part of any solution to the conflict. A weekend meeting in Geneva of major world powers convened by Kofi Annan, the special envoy representing the United Nations and Arab League, failed to reach a consensus on the removal of Mr. Assad, with representatives agreeing instead to a transition plan that seemed unlikely to succeed.

At the United Nations in New York on Monday, the organization’s top human rights official, Navi Pillay, told the Security Council that it should strengthen the 300-member observer mission in Syria, which suspended operations last month because conditions were too dangerous. Ms. Pillay, the high commissioner for human rights, also said the flow of weapons to Mr. Assad’s military and the insurgency was increasing.