BEIJING -- China strongly condemns an attack on United Nationspeacekeepers in South Sudan, a Foreign Ministry spokesman said Wednesday.

"The Chinese side strongly condemns the violent act of attacking UN peacekeepers in South Sudan," Hong Lei said at a regular press briefing.

On Tuesday, unknown militants ambushed the UN Mission in South Sudan, killing five UN peacekeepers from India and at least seven civilians.

"Any actions of attacking or threatening UN peacekeepers are unacceptable," Hong said.

He expressed China's sorrow for the victims and offered condolences to their families.

"The Chinese side urges all parties concerned to adopt effective measures to guarantee the safety of UN peacekeepers," he said.