The European Union is preparing further sanctions against Syria, including a possible ban on commercial air flights and a freeze on central bank assets, although diplomats acknowledge that the bloc has limited means to bring a swift end to the worsening violence, writes Joshua Chaffin in Brussels.

EU diplomats have begun studying a range of options to try to increase pressure on President Bashar al-Assad’s government, whose escalating bombardment of the city of Homs has claimed 150 lives this week, according to opposition estimates that cannot be independently verified.

The UN’s human rights chief condemned “the Syrian government’s wilful assault on the city of Homs, and its use of artillery and other heavy weaponry in what appear to be indiscriminate attacks on civilian areas in the city”.