Opposition fighters have seized control of a number of Syria's key border crossings after clashes with the army on the bloodiest day of the uprising against President Bashar al Assad.
They also attacked the main police station in the capital Damascus in another sign that the rebel movement is at its strongest since the 16-month uprising began.
Officials in neighbouring Iraq said Syrian rebels were in control of the Syrian side of the main Abu Kamal border checkpoint on the Euphrates River highway, one of the main trade routes across the Middle East.
A senior Iraqi army official said 20 soldiers and their commander had been killed at the Syrian army outpost in the remote Sinjar mountain range, near the Iraqi border.
Television pictures also showed rebels in control of the border crossing of Bab al Hawa into Turkey at one point but it has been reported that they later withdrew.
They showed fighters taking down pictures of Mr Assad and his late father Hafez who ruled before him - images of a buckling dynasty.
There are reports that opposition activists also managed to seize the Jarablus crossing into Turkey in what appears to be part of a co-ordinated campaign to seize strategic crossing routes.
In the fall of other Arab countries, such as Libya, who controls the borders is interpreted as a preliminary indicator of a regime losing its grip on authority.
In Damascus a witness in the central old quarter district of Qanawat said the huge headquarters of the Damascus Province police was black with smoke and abandoned after being torched and looted in rebel attacks.
"Three patrol cars came to the site and were hit by roadside bombs," said activist Abu Rateb.
"I saw three bodies in one car. Others said dozens of security men and pro-Assad militia lay dead or wounded along Khaled bin al Walid street before ambulances took them away." The activist’s account cannot be independently verified.
Mr Assad added to the sense of his regime being significantly weakened by failing to appear on television immediately after the deaths of three of his inner circle in a massive bomb blast on Wednesday.
His brother-in-law, his defence minister and a top general were all killed. The head of intelligence and the interior minister were wounded.
Syrian rebel at the Bab al Hawa crossing
Mr Assad was finally shown on television on Thursday swearing in a new defence minister, though the precise location for the pictures was not clear.
But the leader still commands enough authority within the armed forces to order helicopter gunships into the skies in Damascus to pound rebel neighbourhoods.
The next key indicator of how long Mr Assad can hang on for will be an assessment of the strength of the army and its loyalty to him.
There had been reports that he had gone to the coastal town of Latakia where he has a presidential palace.
Latakia provides an easier location from which to make an escape if the president reaches the conclusion he has no option but to leave Syria.
There have been further reports that Syria’s irst lady, Asma al Assad, has fled to the Russian capital Moscow. Again these are unsubstantiated.