David Cameron said his proposal was in no way an invitation for the Syrian leader to settle in Great Britain, the Financial Times reported.
"Of course I would favor him facing the full force of International law and justice for what he has done," Cameron said during the first day of a three-day visit to Saudi Arabia. "I am certainly not offering him an exit plan to Britain but if he wants to leave, he could leave, that could be arranged."
The British prime minister ruled out arming the Syrian rebels, saying Britain had to obey international law but could increase humanitarian aid.
The brother of the speaker of Parliament in Syria was assassinated Tuesday by anti-government rebels, state-run news agency Syrian Arab News Agency reported.
The assassination of Mohammad Osama al-Laham came as clashes between the government and the opposition wracked most major cities, The New York Times reported. At least 162 people were killed Monday in Idlib province and Damascus and its suburbs.
Laham was the brother of Jihad Laham, the speaker of the People's Assembly. Laham held a doctorate in agriculture and SANA blamed his death on anti-government rebels attempting to eliminate people with skills the country needs.
Laham's death took place the same day Syria's main opposition bloc voted to add activists and political groups from inside Syria amid U.S. pressure for a more representative and cohesive leadership.
The Syrian National Council "agreed to a restructuring plan and to reduce the number of [existing] members of the general secretariat to accommodate 200 new members representing 13 political groups and independents," SNC spokesman Ahmad Kamel said on the second day of a four-day meeting in Doha, Qatar.
Existing general secretariat members doing central administrative duties would be reduced to 220 from 313 to accommodate the 200 new members, Kamel said, adding the group was expected to meet in its reorganized form after a vote Tuesday.
Tuesday's meeting was expected to discuss a U.S.-backed initiative by well-known exiled dissident Riad Seif to create a larger umbrella group the SNC would be part of but not dominate.
The new 50-member group, called the Syrian National Initiative, would form the basis of a government in exile. It would include 15 SNC members, with the remaining seats filled with representatives of rebel fighters, opposition military councils and minority groups such as Kurds, Syria's largest ethnic minority, as well as minority Christians and Alawites.
Assad and many of his top security chiefs are adherents of the Alawite sect, an offshoot of Shiite Islam.
SNC members planned to meet with Seif and supporters Thursday. Four days of internal SNC meetings are to end Wednesday.
The unified government in exile is envisioned being formed as early as next month, the BBC reported.
The exile government of technocrats would then hold a conference in Morocco to gain international recognition, Seif said.
The Doha meeting took place as some of the worst violence in months racked Syria, with residents of southern Damascus fleeing heavy shelling and smaller towns shattered by air attacks.