Prime Minister Hun Sen said yesterday he was not responsible for the presence of Vietnamese people in Cambodia, explaining that many immigrants put down roots here after the French colonial authorities brought them in to work on their rubber plantations.

A fluent speaker of Vietnamese, Hun Sen was installed in power during Vietnam’s occupation of the country in 1985 and has battled claims of subservience to the country’s historical enemy, including turning a blind eye to rampant illegal immigration.

During a speech in Tbong Khmum province, which borders Vietnam and has long had one of the country’s highest concentrations of rubber fields, Hun Sen called on younger generations to educate themselves on the history of migrations from Vietnam.

“The Vietnamese people did not come and live in Cambodia during the present time; the French brought them here,” Hun Sen said after officially unveiling a new paved road in the newest province.

“They insult only me, the younger generation, [but] the Vietnamese people were brought here by the French to tap the rubber trees, and 70 percent of the tappers were Vietnamese,” the premier continued. “As they do not know the history, they curse only me, the younger generation. Be careful about bad karma.”

Hun Sen’s historical connection to the Vietnamese government and the apparent ease with which immigrants from Vietnam have been able to settle in Cambodia under his reign have long served as one of the opposition’s most effective talking points.

The weekend death of former prime minister Pen Sovann – who Vietnam removed from power in 1981 after he reportedly opposed it on a number of issues, including migration – has also renewed commentaries on Hun Sen’s relationship with Vietnam.

Since the Cambodia National Rescue Party’s surprise gains at the 2013 election, Hun Sen’s government has also carried out a high-profile campaign to arrest and deport Vietnamese people living and working in Cambodia without proper documents.

Sok Phal, director of the Interior Ministry’s general department of immigration, which has led much of the deportation campaign, declined to comment on Hun Sen’s remarks yesterday. However, in October last year, he said that he believed there were 160,000 illegal Vietnamese people living in Cambodia.

Yet estimates from the opposition, which has itself come under fire for attempting to stoke racial tensions for electoral benefits, have at times been much higher, reaching to the hundreds of thousands.

The issue remains emotional for many Cambodians because the country’s loss of sovereign control of most of southern Vietnam was preceded by large-scale immigration from the north. Many fear that Vietnam still has designs to take the rest of Cambodia.

However, many ethnic Vietnamese in Cambodia were born here, with families going back generations. Many have lived on rivers for decades to skirt laws on foreigners buying real estate and do not have citizenship in either Cambodia or Vietnam.

CNRP spokesman Yem Ponhearith said that the time period that any illegal immigrants living in Cambodia arrived was less important than ensuring immigration laws are enforced, and that he hoped the government would continue with its deportation program.

“Our country has laws on immigration and nationality, and the government has implemented some – for example, by deporting illegal Vietnamese immigrants back to Vietnam,” Ponhearith explained. “We will continue to urge for further implementation.”