And the scandal comes at a testing time in a nation where parties from Dutch-speaking Flanders and Francophone Wallonia are discussing greater regional autonomy from a federal state of which the monarchy is a primary symbol.

Belgium has long had difficult relations with Congo, its former colony, making any trip there a test of diplomacy.

Prime Minister Yves Leterme said Wednesday he “regretted” this month’s trip because such visits can be seen as carrying a political message. Foreign Minister Steven Vanackere said that, as a royal, the prince doesn’t enjoy the freedom of unfettered travel. An opposition party said it would reopen in parliament an old debate over the size of the royal stipend.

For years, Prince Laurent has courted controversy, including though his love of driving cars at high speed.

Now he has put his foot into the delicate game of diplomacy and foreign affairs by going to Congo recently on a trip his legal adviser has said was linked to scientific work on deforestation.

Prince Laurent’s great-great-grandfather, Leopold II, ran Congo Free State as a private property in the late 19th century and became extremely wealthy from the sale of ivory and rubber. His reign, however, was considered among the most savage and ruthless of colonial times.

A visit from a descendant makes a trip all the more controversial.

“I had tried to dissuade him and made it clear, in writing, that the government regretted there was no consultation beforehand,” Leterme said during a royal visit to Germany.

Such direct political criticism of the royal family is very rare in Belgium, where the monarchy is seen as a glue between the country’s 6 million Dutch-speakers and 4.5 million Francophones.

“The prince is not an average citizen and such a visit does have a political dimension,” Leterme said. “I will contact the prince over the coming days to clearly discuss this.” At a time when protracted government negotiations between the linguistic groups are questioning the core issues holding the nation together, a royal scandal adds spice to the debate.

The biggest party in Dutch-speaking Flanders, the N-VA, which seeks Flemish autonomy, has long been a critic of the royals and most things Belgian, and immediately announced moves to introduce a bill to cut royal stipends.

“The taxpayer doesn’t have to put up with the tomfoolery of Laurent,” said N-VA parliamentarian Theo Francken. He said such stipends should be limited to the monarch and the heir, instead of all children of the king. He also called for cost-cutting and more transparency in how public money is spent.

Vanackere said that receiving any stipend involved responsibilities and consultation on such things as travel.

“You cannot have your cake and eat it too,” he said on VRT network.

The royal family said that Laurent’s annual stipend totals some €270,000 ($380,000) based on 2001 prices. Francken said it translated to €312,000 ($440,000) last year.

In comparison, President Barack Obama earns $400,000 a year plus travel and entertainment allowances.