Prime Minister Hun Sen advised the country’s newest crop of teachers not to feel down about their poor salaries, recalling that were they embarking on their careers in the aftermath of the Khmer Rouge regime their pay would be a few bags of rice each month.

The prime minister’s recollection of the situation in the country 35 years ago follows a recent teachers’ strike for higher wages, and calls by the opposition CNRP for better pay for all civil servants.

Mr. Hun Sen shared his memories on Tuesay before personally handing out some of the 1,038 new teacher certificates at a graduation ceremony at the National Institute of Education in Phnom Penh, and reminding his audience that the world was not an equal place.

“We should remember our past, when teaching was exchanged for milled rice,” Mr. Hun Sen said.

“After teaching was exchanged for milled rice, we started to exchange teaching for nine kinds of goods,” including kerosene, he said.

“How difficult it was,” he remembered.

Since the fall of the Khmer Rouge in 1979, Cambodia has gradually built up the ranks of its public school teachers to just over 110,000 today.

“So paying their salaries every month is not a small story,” said Mr. Hun Sen, who has led the country for the past 29 years, the last 10 of which have seen strong GDP growth and the emergence of a super-wealthy class in the country—many with links to the prime minister’s ruling CPP.

Mr. Hun Sen said raising teachers’ salaries was a gradual, ongoing job and that having rich people and poor people was the way of the world.

“We need to go step by step with government reform, even if our salaries are not enough or what we want,” he said.

“If everyone in the world had the same salary, everyone would have money equal to Bill Gates and the world would have no problems,” he quipped.

Instead, Mr. Hun Sen added, “the world always has rich people and poor people, and there are people who have high salaries and low salaries, this is very normal.”

Before wrapping up, Mr. Hun Sen made a thinly veiled dig at the opposition—which has been calling for a $250 minimum monthly wage for teachers and all other civil servants since last July’s national election—referring to CNRP leader Sam Rainsy as an “example” prime minister.

“If you are just an example prime minister, it’s no problem,” he said. “But the real prime minister speaks and has to do.”

Mr. Hun Sen regularly harkens back to the Khmer Rouge years of three decades ago and their immediate aftermath as a rule by which to measure his own achievements. He leaned heavily on that old trope during last year’s national election, which saw his party suffer a stunning loss of votes.

Though his party officially won the vote yet again, it did so by its narrowest margin in 20 years. Observers attributed that loss in popularity to a younger electorate for whom Mr. Hun Sen’s references now mean little.

Opposition CNRP leader Sam Rainsy said Tuesady that 30-year-old comparisons were “meaningless,” but the only way the prime minister could put a positive spin on his own shoddy record.

“The Khmer Rouge [was] hell, so anything would be better than hell, so it’s easy to say it is better [now] than hell, it is too easy,” Mr. Rainsy said of Mr. Hun Sen’s advice to teachers.

“His performance is so poor any comparison to neighboring countries or recent examples, he would look very bad,” he added.

The opposition has long accused the government of spending too much on national defense and public security at the expense of education and health. Though the latest national budget boosted education spending by some 20 percent, it still comes in under 2 percent of the country’s $17.2 billion gross domestic product for 2014 as projected by the World Bank.

Rong Chhun, president of the Cambodian Independent Teachers Association (CITA), who organized a brief and spotty strike for a $250 monthly minimum wage in January, said the prime minister should be looking for comparisons elsewhere.

“He should not be comparing the teachers’ situation to the situation 30 years ago. We should be comparing it with other countries such as Thailand, Vietnam, and Malaysia,” he said.

Kim Darany, 53, also had little use for Mr. Hun Sen’s history lesson.

A 33-year veteran of Cambodia’s public education system who now teaches elementary school in Pursat province, she can remember having her modest pay supplemented with handouts of rice and kerosene in the early 1990s. But she has also seen the average lot of teachers improve little while a small elite around Mr. Hun Sen’s family has grown rich.

“If we compare Mr. Hun Sen and his group to us teachers since the past, he and his group has got more and more rich but teachers are as poor as before,” she said. “Their children can study overseas, but my children don’t have the money to go to university.”

(Additional reporting by Zsombor Peter)

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