Myanmar 'sorrow' over China deaths amid rebel conflict
Myanmar has expressed "deep sorrow" over the death of Chinese nationals amid a conflict with rebels in the Kokang region bordering China.
Chinese authorities said a bomb fell from a Myanmar aircraft onto a field in Yunnan province on Friday, killing five people and wounding eight.
At the weekend, a senior officer said China's military would take "decisive" measures if there were more incidents.
Officials in Myanmar have said rebels could be to blame for the bomb.
"We would like to express our deep sorrow for [the] death and injuries of Chinese nationals living in [the[ border area," Myanmar's government said in a press release in the state-run Global New Light of Myanmar newspaper.
The statement said the foreign and defence ministries of both nations were in contact over the incident.
It said an investigation would be launched into whether the Kokang insurgent group was involved in the incident so as "to have a negative impact on the friendship between Myanmar and China and to create instability along the border area".
Since the incident, China's air force has sent fighter jets to patrol the China-Myanmar border areas. China has also lodged an official protest with Myanmar's ambassador to China.
The BBC's Myanmar correspondent, Jonah Fisher, says there is too much shared interest for Beijing and Nay Pyi Taw to fall out completely.
But events along the border near Kokang are putting the relationship under ever increasing strain, he says.
Clashes between Myanmar's military and rebel fighters known as the Myanmar National Democratic Alliance Army (MNDAA) have intensified since February.
The government has declared a state of emergency in the rebels' base in the Kokang region.
The fighting was triggered by the return of rebel leader Phone Kya Shin after five years of exile in China.
Myanmar (formerly known as Burma) has accused former Chinese soldiers of training the rebels - an allegation denied by the rebels. China has also rejected any links with the rebels.