Iraq has asserted that al-Qaeda fighters are streaming out of the country to carry out attacks across the border in Syria, on the same day the head of the UN observer mission said violence there had reached "unprecedented levels".
"We have solid information and intelligence that members of al-Qaeda's terrorist network have gone to Syria," Hoshyar Zebari, Iraq's foreign minister, told reporters in Baghdad on Thursday.
Zebari did not elaborate or provide details but said his main concern is "extremist, terrorist groups taking root in neighbouring countries".
UN Secretary-General Ban Ki-moon has said he believes al-Qaeda was responsible for two suicide car bombs in Damascus in May that killed at least 55 people.
Rebel fighters have launched increasingly deadly attacks on government targets, and several suicide bombings that bear the hallmark of al-Qaeda in Iraq indicate extremists are joining the fray.
Opposition activists and the rebel Free Syrian Army deny having any links to terrorism and say they do not have the desire or the capabilities to carry out massive suicide bombings and other al-Qaeda-style attacks. But dozens of rebel groups are operating in Syria with little or no co-ordination between them.
Military defections also have been on the rise.
The Britain-based Syrian Observatory for Human Rights and other opposition websites said on Thursday that Brig Gen Manaf Tlass, a member of the elite Republican Guards and a son of a former defence minister, had defected and fled to Turkey. If the reports are confirmed, the defection would be a major blow to Assad.
Tlass is a top Sunni general in a government made up mostly of members of President Bashar al-Assad's Alawite sect and was once a close confidant of the president's.
The Observatory quoted "multiple sources" in Syria as saying that Tlass had left Syria and was expected to formally announce his defection. Turkey did not immediately confirm the reports.
Al Jazeera could not verify the defection of Tlass, whose father Mustapha served as defence minister for 30 years under former president Hafez al-Assad, Bashar’s father.
A news website close to Assad's security services quoted a Syrian official as saying Tlass was in Turkey.
The Syriasteps website also had official playing it down: "His desertion means nothing," he said. "If Syrian intelligence had wanted to arrest him it would have."
'Friends of Syria'
But a source in the exiled opposition to Assad, who said a relative of Tlass had confirmed his defection to him, said: "It's a very important defection. His brigade is very attached to their general, so we can say the true defection has started."
That source said Tlass had fled Damascus on Tuesday and was in Turkey en route for Paris, where Western and Middle Eastern sponsors of the rebel cause are meeting as the "Friends of Syria" on Friday. The French capital is also the home of Tlass' sister, the widow of a billionaire Saudi arms dealer.
In-depth coverage of escalating violence across Syria
A witness in Damascus, who spoke anonymously for fear of the security services, said Tlass' house in the Syrian capital had been ransacked by security agents on Thursday: "They took away everything," the witness told the Reuters news agency.
Another opposition source said Tlass was expected to issue a video message soon announcing he was joining the opposition.
His departure alone is unlikely to affect greatly the capability of the Syrian army but will be seized upon by Assad's enemies in the West as well as at home.
Also on Thursday, the secret-spilling group WikiLeaks said it was in the process of publishing material from 2.4 million Syrian emails - many of which it said came from official government accounts.
WikiLeaks' Sarah Harrison told journalists in London on Thursday that the emails reveal interactions between the Syrian government and Western companies, although she declined to go into much further detail.
Harrison quoted WikiLeaks founder Julian Assange as saying that "the material is embarrassing to Syria, but it is also embarrassing to Syria's external opponents."