China called for an end to the fighting between the military and rebel forces in Myanmar’s northern Kachin state and rebuked the country’s government, a close ally, after an artillery shell fell into Chinese territory for the second time in a month.

Myanmar’s military has stepped up its campaign against the Kachin Independence Army in recent weeks, using air strikes and artillery to strike close to rebel headquarters in Laiza, near Yunnan on the Chinese border.

The shell landed 500m inside China on Tuesday, said China’s foreign ministry spokesman, Hong Lei. He did not say whether Beijing believed the shell was fired by Myanmar’s military or the rebels but told a press briefing that China had made “immediate emergency representations to Myanmar, expressed strong concern and dissatisfaction with the situation, and demanded that Myanmar earnestly investigate and adopt a series of measures to prevent further similar occurrences”.