Myanmar military operations against an ethnic insurgent group forced tens of thousands of refugees across China's southern border.
By the weekend, more than 30,000 refugees had fled from northeastern Myanmar into China
The clashes come amid the junta's attempts to exert its authority over border areas before elections are held next year. Three days of fighting killed 26 government soldiers and at least eight rebels.
Some analysts believe the guerilla forces have suffered heavy casualties and that at least one-half of their estimated 1,500 armed forces have fled into China.
At least 700 soldiers handed over their weapons to Chinese authorities as they crossed the border, discarded their green military uniforms and donned blue overalls supplied by their Chinese hosts.
Beijing deployed extra troops and armed policemen to the area to guard against a possible spillover of the violence across its border. A senior Chinese envoy was dispatched to the Myanmar capital at Naypyidaw to convey Beijing's "serious concerns" about the situation, according to a senior Chinese government official.
Refugees began to return home on Monday following the end of fighting. Yunnan provincial government spokesman Li Hui said at least 4,000 refugees had returned to Myanmar by the end of the day.
However, the number of returning refugees fell sharply on Tuesday, with about 30 seen returning during a half-hour period at the Nansan border crossing.
Many thousands remained in Yunnan and it was not clear whether they intended to stay or return. Chinese officials refused to release information about the latest situation on Tuesday morning and ordered foreign journalists to leave the area.
The crisis showed how Myanmar's ruling military junta can sow instability that spills into China, prompting a rare request from Beijing last week that the generals calm the situation and protect the interests of Chinese nationals there.
Moreover, Myanmar's decision to launch the attack so near the Chinese border was seen as a snub to Beijing by some analysts. One Chinese official said that Chinese central authorities were "extremely upset" by the spillover effects of the Myanmar military's actions and were "furious" that they had not been forewarned about the offensive.
After a flurry of diplomatic contacts, both in Beijing and Naypyidaw, Myanmar has "apologized" for the instability caused across the Chinese border, according to a Myanmar Foreign Ministry official.
As a sign of more troubles to come, Aung Din, executive director of the US Campaign for Burma, said Myanmar forces were continuing to pour into the north-east, confiscating private vehicles along the way.
Return to Myanmar slows, 1 September 2009,
Myanmar refugees begin to return home from China, 1 September 2009,
Border war rattles China-Myanmar ties, 1 September 2009,