Gathered around fires lit on the pavement or lying down under make-shift plastic tents amid near freezing temperatures, they eye curiously the passers-by, some of whom bring them food or blankets.
"We are here because we have no jobs and no money," said a young man, through an interpreter, while asking to remain anonymous.
"I paid 40,000 yuans (or 3,640 euros) to a Chinese recruiting company who promised to find me a job in construction, but I only worked for one month and got 100 euros," he added.
According to him, about 800 countrymen were sharing his lot.
Short of manpower, Romania, which enjoyed a construction boom in recent years, recruited about 4,500 Chinese in 2008.
But as the the crisis began to hit, many building sites have been closed down and thousands of workers laid off.
"What we want is to recover the guarantee we paid to the intermediaries and go back to China," said another worker, Zhang Li, 54, as the others nodded approvingly.
"We were told we would get good salaries and decent living conditions but we have been deceived," said Huang, 36, carefully unfolding a sheet of paper reading, in Romanian, his labour contract had been terminated because of his "refusal to work".
But Ran Azor, the president of the Israeli-based Stone Group, whose Romanian branch Eurostone Developer is one of the most active Chinese manpower recruiters, said he was puzzled by the immigrants' sit-in.
"Can you understand Chinese mentality?", he told AFP, accompanying his words with a gesture of impotence.
According to him, the company was paying "a lot of money to the workers, up to 1,200 euros per month if they work hard". The net average salary in Romania barely tops 350 euros a month.
Instead, the Chinese immigrants "are listening to bad leaders" and refuse to work, Azor complained.
"We have many projects but the workers are actually killing us," he added, putting the company's losses so far at "about 500,000 to 600,000 euros".
On a building site in Bucharest where several dozen Chinese are still at work, Li, 40, said, after a long silence, he had made "up to 900 euros a month".
Wearing jeans and a protection helmet, the worker said he "did not know anything" about the reasons of his countrymen's protest.
The Chinese embassy said in a communique it had solved the situation of 234 workers, most of whom were flown back to China, and trying to do so for 54 more persons.
"Another 30 Chinese workers however have refused the lodging offered them by their employers and chosen to sit-in in front of the embassy," the communique added.
The marketing manager of Eurostone Developer, Florin Mazilu, said the Chinese protesters "are manipulated by fellow countrymen trying to make a profit out of their situation, or by the Chinese mafia who threaten and even beat them in order to prevent them from going back to work".
But to Gabriel Ghelmegeanu, chairman of the Romania-China Chamber of Commerce, none of these allegations are true.
"The truth is that several intermediary companies have put the Chinese to work for two or three months before telling them they would not be paid," he told AFP.
"What is going on right now is the combined result of the economic crisis and the desire of some companies to make a lot of money at the expense of immigrants," he added.
Ghelmegeanu suggested the Romanian authorities should look more closely at the labor contracts signed by the Chinese workers.
"They might just discover that some of them are not legally employed," he said.