UN human rights investigators have listed the names of 50 regime figures who could be prosecuted by the international criminal court (ICC) for crimes committed against civilians during the violent crackdown on pro-democracy demonstrators.
The list is believed to contain officials inside president Bashar al-Assad's inner circle and security agencies. It marks the first time that government insiders have faced the spectre of criminal charges since the five-month uprising began.
A decision on whether to refer the names to the ICC is likely to be made on Thursday.
Diplomatic pressure on the Syrian government will increase further if, as expected, the US president, Barack Obama, calls for Assad to leave office.
US officials said that Obama will release a written statement, with his first explicit call for the Syrian leader to stand down. Washington is also expected to put further sanctions on Syria.
The US has calibrated its response to the violence in Syria, wary of Damascus's role as a strategic key to the Arab world and the risk that crisis could be exported beyond its borders.
The US has also been cautious about putting its authority on the line, fearing damage to its standing if Assad were to defy its calls for him to go.
The UN report accuses officials of torture, summary executions and abuse of children – allegations that could amount to crimes against humanity. It says security forces have indiscriminately fired at demonstrators, sometimes from helicopters.
It also says injured protesters have been killed inside hospitals, sometimes being locked alive in mortuary freezers. It says Syrian officials confirmed that around 1,900 demonstrators had been killed by mid-July. Hundreds more have been killed since then.
"Children have not only been targeted by security forces, but they have been repeatedly subject to the same human rights and criminal violations as adults, including torture," the report said.
The report's authors were denied access to Syria and spent four months interviewing defectors and demonstrators who had fled the country. Dozens of former members of the security forces have made their way to Amman, and Istanbul, where they have detailed orders given to them by senior officers to attack demonstrators who have demanded Assad leave office.
Activists and defectors have also compiled details of alleged atrocities committed by troops whose commanders insist are targeting terrorists holding their local communities to ransom.
The communities themselves have regularly painted a diametrically opposed version of events, claiming that the armed men terrorising them are government-backed militias, known as al-shabiha or ghosts, who work with security forces.
One defector, a conscript who was deployed to the southern city of Deraa in April, told the Guardian that his unit's first order was not to shoot at armed men. "The officer said they were with us," the soldier said. "They said we were only to shoot at the demonstrators."
In a telephone conversation on Wednesday night with UN secretary general Ban Ki-moon, Assad said the operations in the restive Syrian cities of Latakia and Homms had finished. However, activists on the ground reported on Wednesday that security forces were still active in both places.
In Latakia, a Mediterranean port city that has been the subject of a four-day military assault, security centres were overflowing with detainees, and hundreds of prisoners were being held in the city's main football stadium and a cinema.
The push into Latakia ordered by commanders this week came under strident criticism from other nations in the region, with Saudi Arabia, Bahrain, Tunisia and Qatar withdrawing their ambassadors and Turkey warning Damascus it had uttered its "last words" on the crackdown.