Leterme had stepped in, his spokesman said, but declined to say whether the prime minister had spoken to his Congolese counterpart Antoine Gizenga or with President Joseph Kabila, or to divulge details of the conversation.

Relations between the two countries have been strained since Belgian Foreign Minister Karel De Gucht criticised the Congolese government over human rights, corruption, and its dealings with China during a visit to Congo last month.

Congo has withdrawn its ambassador for consultations and said it planned to close its consulate in Belgium's northern port city of Antwerp. Belgian media said Congo had also asked Belgium to close its consulates in Lubumbashi and Bukavu.

Leterme held a meeting of core cabinet members on Monday evening and decided he would personally intervene. He is due to report back on Wednesday.

De Gucht has insisted he was right to air his views.