China's People's Liberation Army on Monday set to work strengthening its presence along the border with Myanmar after the deaths of five people on its side of the border in Yunnan province fueled growing tensions between the two Asian neighbors.



Residents of Yunnan's Nansan township said two of the PLA's fighter jets were using a local high school sports field as a temporary airfield.



"We have been able to see the build-up of military forces in the direction of the border from here," a Nansan resident surnamed Xu told RFA.



"I have seen military vehicles carrying equipment and some artillery or big guns, [but] I don't know what they are," he said.



China's Sina news website on Monday said the PLA had sent "large numbers" of ground and air forces to Lincang, including anti-aircraft missiles and J-7 fighter jets.



J-10 and J-11 aircraft had been deployed as a second line of defense, it said.



The PLA has recently upgraded the J-7 aircraft with new engines, avionics systems, omnidirectional radar and missiles, Sina quoted PLA air force Col. Yue Gang as saying.



Xu said local people felt more confident with the arrival of the PLA reinforcements.



"We are afraid there will be war, but when we see the army move in, we feel fairly confident," Xu said. "I think we should be able to beat them back, and stop them encroaching over here."



A resident of Mengding who declined to be named said he wasn't worried by the incident.



"Of course we have to act, and to be watchful, but I'm not worried," the resident said. "Let them come; we'll kill them all, one by one."



A Nansan resident surnamed Jiang said he had been watching out for planes and helicopters.



"A lot of [PLA forces] are here, including aircraft, and we see Chinese aircraft sometimes, but they are helicopters," Jiang said.



He said local people believed that Friday's bombing was deliberate on the part of the Myanmar army. "But I don't know if that's true or not," Jiang said.



Protecting conflict zone



A retired PLA officer surnamed Deng, who is currently helping out the rebels, said one of the main security concerns for China is to prevent the outflow of Chinese citizens to the conflict zone, however.



"Now the armed police is stationed all along the roads, checking people's ID," Deng said. "It's the same in Lincang and Nansan."



Xu said the mountainous region of Yunnan bordering Myanmar's northeastern Shan state lacks space for aircraft, however.



"There aren't very many places to station aircraft around here, so they are using any wide, flat spaces, and they are making temporary use of the high school sports field," he said.



Xu said civilian flights in and out of nearby Lincang airport had been grounded since the arrival of the PLA in the region.



"This is because the military aircraft want to come in and out of Lincang," he said. "Military aircraft have been flying patrols over Mengding and Nansan in the past couple of days."



Photos posted online by local residents showed a number of the PLA's Chengdu J-7 interceptor fighter jets parked at Lincang airport on Sunday.



An employee who answered the phone at Lincang Airport on Monday confirmed the grounding of civilian flights, but said it had been temporary.



"That's right, [civilian flights] were canceled," the employee said. "Air China was grounded on Sunday and Saturday, and it was only Air China. China Eastern Airlines was able to fly as normal."



"All civilian flights have returned to normal now," the employee said, but added: "This airport is dual use: civilian and military."



Myanmar response



The PLA response came as Myanmar expressed "deep sorrow" on Monday for the deaths of five people in Yunnan in a bombing that Beijing said was clearly carried out by government planes.



"We would like to express our deep sorrow for [the] death and injuries of Chinese nationals living in border areas as a consequence," the government said in a statement published in the state-backed Global New Light of Myanmar newspaper.



But the government stopped short of taking full responsibility for the bombing.



"[A] thorough investigation will also be made whether the Kokang insurgent group is involved in this incident to have a negative impact on the friendship between Myanmar and China and to create instability along the border area."



But Beijing has said Myanmar's air force is clearly responsible, and has summoned Myanmar diplomats in a strong protest at the incident, which has also prompted a wave of public anger online inside China.



"The facts are clear that a bomb from a Myanmar military plane caused the death of Chinese people," ministry spokesman Hong Lei told a daily news briefing in Beijing.



"We once again urge the relevant parties in the Myanmar conflict to treat China's concerns seriously, maintain restraint, quickly pacify the situation and recover peace and stability in northern Myanmar," Hong said.



A spokesman for Kokang rebel alliance said that the forces allied with the Myanmar National Democratic Alliance Army (MNDAA) have no heavy military hardware in their possession, however.



"Firstly, we have no heavy weaponry of that kind, and secondly, our forces are all directed at Laukkai, with our backs to the border," the spokesman, who gave only his surname Song, told RFA.



He said the Myanmar government was deliberately trying to point the finger at the Kokang rebels.



"They are under a lot of pressure at the moment, what with the student movement domestically, and strikes, so they are deliberately setting out to frame us," Song said.



Fighting began on Feb. 9 in Laukkai between Myanmar government troops and rebel forces after ethnic Chinese commander Peng Jiasheng began his bid to retake the Kokang self-administered zone, which the MNDAA had controlled until 2009.



Tens of thousands of civilian refugees have been driven away from the conflict zone, with an estimated 100,000 sheltering across the border in Yunnan in early March.



Reported by Xin Lin for RFA's Mandarin Service, and by Wen Yuqing for the Cantonese Service. Translated and written in English by Luisetta Mudie.