The first three defendants in England and Wales charged with showing support for the banned group Palestine Action have pleaded not guilty to charges under the Terrorism Act.

Jeremy Shippam, 72, of Yapton, West Sussex, Judit Murray, 71, of West Ewell, Surrey, and Fiona Maclean, 53, of Hackney, north-east London, will face trial in March next year for allegedly holding placards saying “I oppose genocide, I support Palestine Action”.

Appearing at Westminster magistrates court in central London on Tuesday, the three all denied the same charge of displaying an article, namely a placard, in a public place, arousing reasonable suspicion that they are a supporter of a proscribed organisation, contrary to section 13 (1) of the Terrorism Act 2000.

The defendants, who appeared before the chief magistrate, Paul Goldspring, were allowed to sit outside the dock as two are hard of hearing and hearing loops could not be found for them.

Since the ban on Palestine Action came into effect on 5 July, 138 people in England and Wales have been charged with showing support for the group, out of more than 1,600 people arrested.

The three in court on Tuesday were all arrested at a demonstration in Parliament Square, central London, on the day the ban took effect. They could face a maximum sentence of six months in jail and/or a fine if convicted. They were released in conditional bail until 16 March.

A group of protesters gathered outside the court building shouting pro-Palestine slogans, waving flags and carrying placards.

The next protest in Parliament Square opposing proscription is scheduled for 4 October, ending a week of planned demonstrations beginning at the Labour party conference in Liverpool.