There is "genuine concern" Premier League footballer Emiliano Sala was on a light aircraft which disappeared between France and Cardiff.
It is feared the Argentine striker was one of two people on board the Piper Malibu, which went missing off Alderney in the Channel Islands on Monday night.
Cardiff City, which signed the 28-year-old from French club Nantes on Saturday, said it was "seeking clarification" as to what happened, a search resumed at 08:00 GMT.
Guernsey police said "no trace" of the missing aircraft had been found. It left Nantes at 19:15 and had been flying at 5,000ft when it contacted Jersey air traffic control requesting descent, the force said. The plane lost contact while at 2,300ft.
Searches were suspended at 02:00 "due to strengthening winds, worsening sea conditions and reducing visibility", police added. Cardiff Airport confirmed the aircraft was due to arrive from Nantes but a spokeswoman said there were no further details.
The Met Office said at the time the aircraft went missing "there were some showers around, but nothing too intense. Wind speeds were not too bad - average speeds were around 15 to 20mph". As the search continued into the evening though, it became wetter and windier.
The flight disappeared off radar near the Casquets lighthouse, infamous among mariners as the site of many shipwrecks, 13km north-west of Alderney. HM Coastguard said the disappearance was not in the UK search and rescue area, but it had sent two helicopters to help.
A spokeswoman said they were assisting Guernsey Coastguard with a search for a light aircraft off Alderney. "HM Coastguard helicopters from Solent and Newquay have been helping to search overnight with nothing found," she said.