The jury in the Millennium Dome diamond heist trial heard today that stink bombs were to be used to frighten tourists and staff.

After raiders smashed their way through the gate in an earth mover they used smoke grenades to keep people away "and create a general atmosphere of panic and confusion", said Martin Heslop QC, prosecuting.

One of them also had, "believe it or not, some stink bombs", he told the Old Bailey.

A Brighton man, 34-year-old Kevin Meredith of Auckland Drive, is among the accused.

Mr Heslop continued: "Probably in view of the smoke being generated and by them wearing gas masks, it was to facilitate an impression that some noxious substance was being used in order to keep people away."

But armed police swooped and arrested them as they tried to break through the three-quarter inch armoured plated glass vault containing the diamonds with sledge hammers and a nail gun.

One allegedly told officers: "I was 12in from pay day."

Police, suspecting there would be a raid, had taken security precautions at the Dome.

Mr Heslop said: "Arrangements were made to keep children away from the danger area. But for obvious security reasons it was not practicable to alert all staff to the possibility of an attack.

"There were almost 40 specialist firearms officers secretly positioned in the Dome itself.

"There were 60 armed Flying Squad officers positioned north and south of the River Thames and 20 armed officers on the river itself.

"In addition, surveillance officers were employed on foot in the area right next to the vault, dressed as Dome employees."

Mr Heslop was continuing his opening for the prosecution in the trial of six men accused of plotting to rob the De Beers Millennium Diamond Exhibition between July 7 and November 8 2000.

The raiders planned to get away by high-powered speedboat across the Thames, allegedly driven by Meredith.

Meredith was arrested by the river police as he waited by the Millennium Pier, Mr Heslop told the court.

Meredith denies conspiracy to rob, as do Wayne Taylor, 35, of Tonbridge, Kent; Aldo Ciarrocchi, 31, of Balaclava Road, Bermondsey, and William Cockran, 48, of Catford, both south east London; Robert Adams, 57; and Raymond Betson, 39, of no fixed address.

The case continues.