Congolese security forces on Thursday released three diamond dealers-two Israelis and one Belgian-who were arrested the day before as they prepared to board a flight to Belgium, the Associated Press (AP) reported.

Congo authorities in the city of Kinshasa gave no reason for either the dealers’ arrests or their release the next day. One of the newly freed dealers would say only that it had been a “plot,” but he refused to say on whose part, the AP reported. “It is now all fine, we were treated very well, and the police apologized 10 times,” said dealer Keller Zoar, an Israeli.

All three dealers work for the Israeli diamond company Ashley, one of five foreign firms authorized to export Congo’s diamonds since the government lifted a diamond export monopoly earlier this year, the AP reported.

They were arrested at the airport in Congo’s capital, Kinshasa, as they were boarding a flight to Brussels, the AP reported. Israeli diplomats in Congo had expressed concern at the overnight detentions, saying initially they had no idea where the men were being held.

Congo is the world’s third-largest exporter of diamonds.

Joseph Kabila, who took over Congo’s presidency from his assassinated father in January, in April revoked a deal that had given the Israeli firm International Diamond Industries sole export rights for Congo diamonds. The monopoly drove much of Congo’s diamond trade into the black market.

Congo is a former colony of Belgium. Antwerp, Belgium, is a major world clearinghouse for diamonds.

JCK