Beijing condemned the violence in Myanmar on Thursday and called for an immediate ceasefire after an artillery shell flew over the border and landed inside China.

The shell was believed to have resulted from the long-standing clash between government forces and the Kachin Independence Army (KIA) as Myanmar steps up shelling and air attacks on the ethnic minority rebels in northern Kachin state, Reuters reports.

The artillery shell landed 500 meters inside China on Tuesday, the second such occurrence since late December. No one was injured in the shelling but it heightened criticism from China.

“China 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,” China’s Foreign Ministry spokesman Hong Lei told reporters.

China raised concerns that the escalating conflict could send refugees into Chinese territory, forcing the government to send soldiers to the border.

Beijing called on both sides to “immediately implement a ceasefire” and “jointly protect the peace and stability of the China-Myanmar border area”.