A shell hit a Roman Catholic church in Aleppo on Sunday where around 400 people were attending mass.

Seven people were injured when the shell hit the Church of St Francis in the Azizyeh residential district, but according to the Franciscan bishop casualties could have been far worse.

Bishop Georges Abou Khazen told Fides news agency: "It was about 5:50 in the evening, inside the church there were at least 400 people and it was the moment of Holy Communion."

He said that the shell had come from an area held by anti-Assad groups and had exploded on the dome of the church rather than penetrating it and landing inside.

"Had the shell exploded inside the church there would have been a massacre," the bishop said.

Aleppo is the largest city in Syria and has been on the front line of the confrontation between the Assad regime and rebel groups since 2012. Both sides have been accused of atrocities, with a favoured regime technique being to drop barrel bombs from helicopters. The Free Syrian Army has been accused of the indiscriminate use of gas cylinders filled with explosives in government-held areas.

The Catholic Archbishop of Aleppo, Archbishop Jean-Clement Jeanbart, has expressed cautious support for the Russian military initiative against rebel forces. Speaking at the launch of Catholic charity Aid to the Church in Need's report Persecuted and Forgotten? a fortnight ago he said bishops he spoke to said "they have now some hope that the problem will be sorted and war will finish since Russia intervened and struck seriously Daesh [ISIS]. That is what they think."