Syrian Ambassador Sami Khiyami was called in for talks with political director Geoffrey Adams as Syrian security forces on Friday opened fire on thousands of protesters, killing at least one.

The shooting took place on Friday in the central city of Homs, said leading human rights activist Mazen Darwish.

The city has seen some of the largest protests during the Syrian uprising against the regime of President Bashar Al-Assad, which started two months ago.

Human rights groups say up to 800 Syrians have been killed since demonstrations began in mid-March, and about 8,000 people detained — including 2,000 over the last two weeks.

Adams said that “unless the Syrian government stopped the killing of protesters and released political prisoners, the UK along with its EU partners would take further measures to hold the regime to account,” the ministry said in a statement. “These measures would include further sanctions targeted at the highest levels of the regime, including travel bans and asset freezing.”

It was the second time in recent weeks that the Syrian envoy had been ordered to explain his government’s actions.

Last month, Khiyami’s invitation to Britain’s royal wedding was withdrawn over the regime’s action.

Germany on Wednesday summoned Syria’s ambassador to Berlin to deliver a similarly stern message, warning that European nations were considering extending travel bans and asset freezes.

Last week, the European Union imposed measures against 13 officials believed to be playing a prominent role in the violent suppression of demonstrations.

The Foreign Office said Adams had called on Syria to allow the UN and other humanitarian organizations immediate access to Daraa and other Syrian cities which have been targeted by regime violence.

Diplomats acknowledge Assad’s regime currently appears unlikely to respond to protesters demands for greater openness and democracy.

“It’s pretty improbable to say the least that the national dialogue which President Assad announced in his speech to the new government a few weeks ago is likely to prosper,” said one Western diplomat, who demanded anonymity to offer an assessment of the Syrian regime.

“It’s hard to see how any serious figures from the opposition movement can sit down with the authorities at a time when Syrian civilians are being arrested, detained, abused while in detention, and killed,” he said.