A private jet that crashed into the Baltic Sea off Latvia after flying half way across Europe from Spain without responding to controllers' calls belonged to German businessman Karl-Peter Griesemann, his company, Quick Air, said today.

The jet, an Austria-registered Cessna 551, left Jerez in southern Spain yesterday afternoon, turning at Paris and Cologne before flying straight out to the Baltic Sea, where it spiralled into the water east of Gotland, flight tracking data showed.

"I can confirm that it was the private jet of our owner, Karl-Peter Griesemann," said a spokesperson for Quick Air, an air charter company based in Cologne.

He declined to confirm a report in Cologne newspaper Express that Mr Griesemann was the pilot and that he was accompanied by his wife, daughter and his daughter's boyfriend.

The cause of the crash is not yet known.

Aircraft from several countries and a passenger ferry headed to the crash site yesterday evening to aid in the rescue operation.

A wreck, a concentrated waste patch and an oil-like slick had been spotted near the crash site, Latvian search and rescue head Peteris Subbota told Latvian television, adding that no passengers had been found.

German and Danish warplanes were sent up to observe the aircraft as it flew blind over northern Europe yesterday afternoon but were unable to spot anybody on board.

Mr Griesemann has been a prominent figure in Cologne, the largest city in western Germany, playing a role in the deeply Catholic city's annual carnival celebrations