The peer was due to fly to Tanzania for a two-and-a-half week family holiday on Wednesday, but will now spend the next week at least behind bars.

The group were charged after an alleged attack on a GM trial farm at Lyng in Norfolk on Monday morning. All the 27 others were released on bail on Tuesday.

Mike Schwartz: Lord Melchett "convinced of immediate and major threat"

All those charged are accused of criminal damage to a crop of maize, and of trying to remove some of the crops.

Thirty people were arrested on Monday but two people, both women, were released without charge.

Lord Melchett, 51, of Ringstead, Hunstanton, Norfolk, was the first to appear at Norwich Magistrates Court where he was addressed throughout the 20-minute hearing as Mr Melchett.

He entered no plea against charges of theft and criminal damage.

Stipendiary magistrate Frazer Morrison adjourned all of the cases until 5 August.

Greenpeace admits action

The protesters, who range in age from 21 to 57 and come from all over the UK, spent the night in custody at Norfolk police stations.

The cost of the damage done to the crops has been estimated at £750.

Greenpeace has admitted organising the action, which it filmed and which was witnessed by several journalists.

"Greenpeace's view is that something needs to be done about the threat of GM crops and the authorities are not and cannot take the correct action, so someone has to do it and unfortunately it has fallen to Greenpeace to protect everyone's interests," Lord Melchett's lawyer Mike Schwartz told BBC Radio 4's Today programme.

List of accused

The other 27 charged are:

• Rachael Murray, 26, from Highbury, London; Lisa Wetherly, 30, from Chessington, Surrey; Margaret Weaver, 43, from Sandhurst, Berks; Malcolm Carroll, 43, from Strafford, Staffs;

• Iain McSeveny, 36, from Gillespie Road, London; Emma Hargreaves, 28, from Tooting, London; Christopher Holding, 21, from Cardiff; Stokely Webster, 28, from Malpas Road, London;

• Timothy Copley, 41, from Harpenden, Herts; Spencer Cooke, 31, from Derby; Michael Uwins, 53, from Wymondham, Norfolk; Emma Protz, 27, from Seymour Avenue, London;

• Andrew Tait, 28, from Arsenal, London; Andrew McParland, 32, from Epsom, Surrey; Joanne Melzack, 51, from Manchester; Alaistair Beveridge, 30, from Aberdeen;

• Nichola Cook, 31, from Diss, Norfolk; Simon Hackin, 33, from Edinburgh; Simon Bowens, 32, from Leeds; Adrian O'Neil, 25, from Beverley, Yorks; Keith Dawson, 26, from Stamford, Lincs;

• Paul Bellotti, 57, from Devonshire Gardens, London; Michael Waldram, 38, from Ravenstone, Leics; Jacqueline Westwood, 41, from Mexborough, Yorks;

• Timothy Hewke, 39, from Highbury, London; Martin Porter, 29, from Harrogate, N Yorks; Brenda Ramsey, 33, from Wanstead, London.