Red Cross director of operations Dominik Stillhart condemned indiscriminate shelling in Donetsk yesterday after employee Laurent DuPasquier was killed by a shell which landed near the aid group’s offices on Thursday.

“We understand that there were other civilian casualties in Donetsk,” he said.

“Indiscriminate shelling of residential areas is unacceptable and violates international humanitarian law.”

Rockets also slammed into a 14-storey central shopping centre on Thursday evening, causing further casualties.

Ukrainian Foreign Minister Pavlo Klimkin blamed the shelling on “terrorists.”

Critics have pointed out however that pro-Kiev forces which control the airport to the north of Donetsk have consistently shelled the opposition-held city from this vantage point.

Four people were killed by a shell that landed on a school in the city on Wednesday and six more died when a minibus was hit, despite a September 5 ceasefire agreement for artillery pieces to retreat 10 miles.

Rebel forces responded to the bombardment by renewing attacks on the airport yesterday, seizing some buildings on its fringes and using them to target the main terminal.

Losing the airport would be a major blow to Kiev and would also allow pro-independence forces to receive large cargo planes from Russia.

UN secretary-general Ban Ki Moon said that the aid worker’s death, along with the shelling of the school, “underscore the fragility of the current ceasefire and the importance of ensuring a secure environment in south-eastern Ukraine that will allow humanitarian actors to carry out their work and deliver critical assistance to those most in need.”