Pilots taking part in a vintage air rally across Africa were being detained on Wednesday by Ethiopian authorities, a spokesman for the trip said.
A dozen biplanes dating from the 1920s and 1930s took off on November 12 from the Greek island of Crete, embarking on a 13,000-kilometre (8,000-mile) journey to Cape Town.
But less than two weeks into their journey the pilots were grounded at Gambella airport in western Ethiopia, close to the border with South Sudan, a spokesman for Vintage Air Rally told AFP.
A Waco YMF-5D biplane sits on the runway on November 20, 2016 in Khartoum airport during the Vintage Air Rally ©Ashraf Shazly (AFP/File)
"They are all in Gambella in Ethiopia and the Ethiopian authorities have decided to locate them at state accommodation for the moment.
"We cannot communicate with them because they (the authorities) have taken their phones and iPads," the spokesman said.
He confirmed all of the pilots participating in the rally had been detained by Ethiopian authorities but did not say whether they faced arrest.
The reason for the pilots being stopped was not immediately clear, with the spokesman saying it may relate to problems with landing permits, although he believed their flight paths had been approved.
Vintage Air Rally's comments come a day after the organisers said a British pilot taking part, Maurice Kirk, had gone missing during the three-hour flight from Sudan to Ethiopia.
The 72-year-old pilot, who joined the rally only on Sunday, was subsequently said by Vintage Air Rally to be safe at Gambella airport with the other participants.
Teams taking part in the rally come from a dozen countries including Canada, France, Germany, South Africa and the United States.
A spokeswoman for Britain's foreign ministry told AFP they were looking into the reports of the pilots being grounded: "We are in contact with the local authorities regarding a group who have been prevented from leaving Gambella Airport, Ethiopia."
The pilots had arrived in the Sudanese capital Khartoum on Sunday, after earlier in November becoming the first group of aircraft to land at Egypt's Giza pyramids in 80 years.
The biplanes had originally been scheduled to arrive in Cape Town, South Africa, on December 17.