A Chinese J-31 stealth fighter jet takes off for a demonstration flight during the 10th China International Aviation and Aerospace Exhibition, also known as Airshow China 2014, in Zhuhai city, south China's Guangdong province, Nov 10 2014. [Photo/IC]

Patrolling over China-Myanmar border has been increased by the People's Liberation Army (PLA) Air Force after a Myanmar warplane dropped a bomb in southwestern Yunnan province and killed four Chinese, a military spokesman said Saturday.

Chinese Air Force has sent several batches of warplanes since Friday to track and keep watch on the Myanmar military planes flying toward the border, said Colonel Shen Jinke, the spokesman for the PLA Air Force.

The Chinese warplanes will send warnings and force the Myanmar planes from approaching Chinese territory, said Shen.

On Friday night, Chinese Vice Foreign Minister Liu Zhenmin summoned Myanmar Ambassador Thit Linn Ohn in Beijing, lodging solemn representations to him after the bomb killed four innocent Chinese people.

The bomb hit a sugarcane field in the border city of Lincang and killed four people working there on Friday afternoon. Nine others were also injured.

Liu condemned the incident and urged the Myanmar side to thoroughly investigate the case and inform the Chinese side of the result.

He also urged Myanmar to punish the perpetrator, appropriately handle the aftermath, and take immediate and effective measures to prevent recurrence of such incidents and safeguard the security and stability in the border areas between China and Myanmar.

Earlier this week, China urged stability in its border area with Myanmar as well as the northern part of the southeast Asian country which have been hit by conflict recently.

"It serves the common interests of the two nations and two peoples," Foreign Minister Wang Yi.

The minister also reiterated that what happened in northern Myanmar is the internal affair of the country.

"We hope the conflict can be resolved peacefully," he said.

China, which adheres to the principle of non-interference in the internal affairs of other countries, has made it clear that it respects Myanmar's sovereignty and territorial integrity.

The relations between China and Myanmar, who share a border line of over 2,000 km, have been upgraded to a comprehensive strategic cooperative partnership.

"We are friendly neighbors, sharing not just mountains and rivers, but also weal and woe," Wang said. "When problems arise in our neighbor's house, we are following the situation very closely."

The minister also pledged continued communication and cooperation with Myanmar, to jointly ensure tranquility in the two countries' border area and safeguard safety of both peoples.