Dozens of Roma (Gypsies) have arrived back in Romania after being repatriated by France under a controversial policy backed by President Nicolas Sarkozy.
At least 70 Roma left France and hundreds more will follow in the coming weeks after their camps were shut down.
The French government says it is a "decent and humane" policy of removing people from deplorable conditions.
But rights groups say the Roma are being demonised, and Romania has warned France against "xenophobic reactions".
"We understand the position of the French government. At the same time, we support unconditionally the right of every Romanian citizen to travel without restrictions within the EU," Romanian President Traian Basescu said.
However, Mr Basescu added that he was prepared to send police to France to help implement the repatriation scheme.
Two flights from Lyon and Paris were due to be carrying 93 Roma passengers, but according to some reports only 70 actually boarded the flights and arrived in Bucharest.
A deportee named Gabriel told the AFP news agency in Bucharest that life had been "very tough" in France, but he would not rule out returning because there was no work in Romania.
Another man said that in Romania "we don't have any chance, no jobs, nothing".
Hundreds more are expected to leave France on flights scheduled for Friday and next week.Exploitation claims
The Roma are EU citizens, mostly from Romania or Bulgaria, but French law requires them to have a work permit and prove they have the means to support themselves if they intend to stay for more than three months.
The Roma have a history of being persecuted - many were killed by the Nazis”
They complain that the permits are difficult to get, and so they are often forced to live illegally.
Roma who agree to leave have each receive 300 euros (£246; $384) and an additional 100 euros for each child.
The French government says it plans to shut down 300 illegal Roma camps in the next three months.
The controversial plan was put in place after clashes last month between police and travellers in the southern city of Grenoble and the central town of Saint-Aignan.
The Roma were not involved in all of the trouble, but the government said travellers' camps were sources of "illegal trafficking" and "exploitation of children for begging, of prostitution and crime".
Some 51 camps have already been demolished by police and the residents have been moved into temporary shelters or accommodation.Popularity booster?
The operation has been condemned by human rights groups, who say it is deliberately stigmatising a generally law-abiding section of society to win support among right-wing voters.
- Roughly 12,000 Roma migrated to France after Bulgaria and Romania's accession to the EU
- Many have no work permits, so live in camps and resort to begging
- Separately, at least 400,000 people are designated "travellers", mostly French nationals with Roma origins
Last week, members of the UN's Committee on the Elimination of Racial Discrimination criticised the tone of political discourse in France on race issues, saying racism and xenophobia were undergoing a "significant resurgence" there.
But France has insisted that the actions "fully conform with European rules and do not in any way affect the freedom of movement for EU citizens, as defined by treaties".
Foreign ministry spokesman Bernard Valero told AFP that an EU directive "expressly allows for restrictions on the right to move freely for reasons of public order, public security and public health".
The European Commission said it would ensure none of the bloc's rules were being broken.
France repatriated some 10,000 Roma last year and other European countries, including Germany, Italy, Denmark and Sweden pursued similar policies.
Mr Sarkozy's political opponents have accused him of using the Roma issue to shift public attention away from corruption and on to crime.
The BBC's Christian Fraser in Paris says that the president's poll rating is sagging and there are some who accuse him of using the recent unrest to boost his own popularity.
Some of the Roma living in France are part of long-established communities of travelling people who are French nationals.
In addition, there are an estimated 12,000 Roma who are recent immigrants from Central Europe.
"Some of these families have been in France for five, seven or 10 years and 300 euros is not enough to help them settle in Romania. They will return in the coming weeks," Malik Salemkour, the vice-president of the French Human Rights League, told the Reuters news agency.