Chinese Premier Li Keqiang said on Sunday that the government had the responsibility and the ability to defend its border with Myanmar, after China said a bomb from a Myanmar aircraft fell in its territory and killed four people.

“We have the responsibility and the ability to firmly defend the stability of the China-Myanmar border, and firmly protect the lives and the security of the property of our people,” Mr Li told a press conference at the end of China’s annual session of Parliament.

China’s military will take”decisive” measures if there is a repeat attack by Myanmar forces on its territory, a senior military officer said.

Myanmar government forces have been battling rebels on the border with China since February and China has urged Myanmar to “lower the temperature”.

But Myanmar denied that any bomb from its forces had fallen in China and said the rebels might have fired into China to create “misunderstanding”. The rebels do not have aircraft.

China’s Air Force has dispatched planes to patrol the border and step up protection of its airspace. Beijing has also summoned Myanmar’s ambassador to complain about the bombing.

Fan Changlong, who is a deputy head of the powerful Central Military Commission, said Myanmar Air Force aircraft had crossed the border “many times” recently, China’s defence ministry said in a statement late on Saturday.

“The Myanmar side must recognise the seriousness of the issue, seriously deal with this incident, punish those who caused the trouble, apologise and pay compensation to family members, and explain themselves to China,” Mr Fan was cited as telling Myanmar’s military in an emergency telephone call. Myanmar must take strict steps to rein in its armed forces to ensure no repeat of such incidents, he said.