THE brother of a convicted terrorist who plotted to attack soldiers in Royal Wootton Bassett says he is worried that hate preacher Anjem Choudray who is facing a lengthy jail sentence may 'brainwash' inmates in the same way he did his brother.

After 20 years of avoiding jail for terrorism Choudray was convicted in July after being found guilty of inviting support for a prescribed organisation under the Terrorism Act but reporting restrictions on the trial and verdict were only lifted this week.

Rob Leech's brother Richard Dart was jailed for six years in 2013 along with two co-conspirators for engaging in conduct in preparation of acts of terrorism.

The former BBC security guard was arrested as he travelled to Pakistan to try and get terrorist training before planning an attack on the military repatriation town.

Mr Leech said Choudary had become a 'father figure' to Dart and he fears the preacher could radicalise more men while he is in prison.

After Dart, of Acton, West London, pleaded guilty, Mr Leech confronted Choudary suggesting he was part of the radicalisation and brainwashing of his brother and many others.

"His words, typically brazen, were 'some brains need washing.' which goes a long way towards explaining what he was about," said Mr Leech who took part in a BBC documentary, My Brother The Terrorist after Dart's conviction.

"Choudray always denied that he had anything to do with facilitating Richard's plans to go and get training with the Taliban but he always admitted that he was responsible for shaping his beliefs and Islamic understanding," said Mr Leech.

Choudary launched an extraordinary defence for Dart after he was jailed, saying he had been locked up for a ‘thought crime’ and had ‘committed no sin and harmed nobody’. He added that 'Jihad training’ is a duty for Muslim men.

"It was obvious he played a large part in Richard's radicalisation and he was able to poison other young men's minds,' said Mr Leech.

Choudray now faces up to 10 years in prison.

But Mr Leech says he is fearful he could become a martyr figure and that he could use jail as an opportunity to radicalise others.

"Maybe it's even worse that he's in prison - it’s ripe pickings for him," he said.

Choudary is believed to have inspired at least 110 Britons into committing terrorist acts. Police also think he helped encourage up to 850 fanatics to travel to Syria to fight for ISIS.

His now-banned radical group, Al-Muhajiroun, has links to 15 terror plots, including the murder of Lee Rigby and the 7/7 attacks.

He was finally snared by police for inciting support for ISIS in a series of online lectures.

Choudary repeatedly provoked the British public with a series of stunts in which his followers burned remembrance poppies and disrupted Armistice Day events.

He also called for Buckingham Palace to be turned into a mosque.