Racing at Ascot was abandoned after just one race today following a security alert.
Police informed officials at Ascot that a coded message had been received as the runners for the Willmott Dixon Cornwallis Stakes were at the start at 1.55pm.
Racegoers were moved onto the course and to the area by the parade ring behind the grandstand while the runners and riders returned to the stables.
At 2.35pm it was announced that the meeting had been abandoned and racegoers were asked to leave the course as police began to search the stands.
Clerk of the course Nick Cheyne told the BBC: 'Unfortunately as the result of a coded message that was received at Charing Cross Hospital and passed on to the police we`ve had to abandon racing.
'The whole of the grandstand has been evacuated and a search will take place and it will take some time to go through the whole of the grandstand.
'We`ve had a coded warning that the police verified as a correct code.
'The first knowledge that Ascot had of it was at five minutes to two.
'The stands were evacuated extremely quickly. The horses for the second race had proceeded to the start so they were well out of the way.
'We`ve now got the horses back and they`re back safely in the stables.
'We are greatly disappointed for everyone, not only the sponsors but all the racegoers.'
The meeting was Ascot`s last Flat card of the season and had already passed a precautionary inspection at 12.30pm following heavy morning rain.
'It looked pretty dismal to start with. We had a precautionary inspection because of all the rain we had this morning. We had the all-clear and then we had this,' Cheyne added.
'We`ve had a very good Flat season and to finish on a note like this when we had such a strong card is very disappointing.'
A Thames Valley police spokesman said the bomb warning was received at 1.25pm.
'Additional police resources have been moved in. No suspicious package has been found,' he said.
The scenes were reminiscent of the infamous 1997 Grand National at Aintree when the big race was abandoned due to a security alert.
The race was eventually run the following Monday with Lord Gyllene claiming the prize in front of a large crowd who had been given free admittance.
Kempton`s biggest meeting was abandoned in similar circumstances on December 27 last year due to a security alert following the King George VI Chase. - PA