The European Union is set to impose a ban on Syrian oil imports, the Foreign Office has said.
The measure would significantly restrict funds for Bashar al-Assad's regime, with exports to the EU worth around a fifth of the nation's income.
The Foreign Office said officials from across the EU had agreed the plan and ministers could sign off the proposals within days.
A spokesman said: "We continue to work with our international partners to increase the pressure on Assad's regime through the EU and UN.
"We have agreement at officials' level to impose an embargo on imports of Syrian oil to the EU, which we hope to have signed off by EU ministers on September 2-3.
"Imports of oil to the EU account for around 20% of Syria's GDP and will cut off a significant source of finance to the Syrian regime."