Miles Cooper is a former primary school caretaker

Miles Cooper, 27, from Cambridge, said he had been angry at authorities and "very concerned about the direction my country was heading in".

Mr Cooper denies 12 charges related to seven letter bombs sent in England and Wales in January and February.

The Oxford Crown Court jury has retired to consider its verdict.

Mr Cooper allegedly sent seven letter bombs, five of which exploded, injuring eight people.

The locations were Abingdon in Oxfordshire; Culham, near Abingdon; Birmingham; Folkestone, in Kent; Victoria in central London; Wokingham in Berkshire; and the DVLA offices in Swansea.

Based on what I learned at school and learned from history books, an authoritarian state eventually develops, and free speech is stifled

Miles Cooper

The UK 'mail bomb' devices

He does not contest that he sent the letters to three forensic science laboratories, a computer company, an accountancy firm, the DVLA and a residential address, but denies intending to cause injury.

Mr Cooper told the jury his anger at the country's authorities had intensified when his father Clive was unable to have DNA samples removed from the police database, even though he had been cleared in 2003 of assault.

"I felt my father had been used and I felt unable to do anything about it," he said.

Mr Cooper added that prior to this, he had campaigned about government's proposals to introduce ID cards, but that his approach changed after the episode with his father.

Mr Cooper said he had been further angered by the treatment of anti-nuclear protesters, and also by an incident involving Walter Wolfgang, then 82, who was thrown out of the 2005 Labour Party conference for shouting "nonsense" at then foreign secretary Jack Straw as he delivered a speech.

He told the court his decision to abandon peaceful methods of protest was "not an easy step to make".

But he said he made the transition "as it became more and more obvious that the government was not going to listen to peaceful protesters and, in fact, they were starting to use anti-terror legislation against them".

'Surveillance society'

He said the letters he sent containing explosive devices were intended to cause fear rather than harm.

They were sent, he added, to organisations he believed were connected to government control, surveillance and monitoring.

"I was hoping to achieve a bomb scare, to shut down a building, but cause no real harm to any individual," he said.

"The overall goal was to shut down certain departments in certain buildings and ultimately to highlight my cause.

"I am genuinely ashamed of what I've done."

Mr Cooper also told the court he had concerns over the amount of power given to the government.

"If you give a small group of people [the government] too much power, they will eventually end up abusing it.

"Based on what I learned at school and learned from history books, an authoritarian state eventually develops, and free speech is stifled.

"Throughout history it has happened over and over again in many other countries."

Referring to the issue of Britain being a "surveillance society", he said: "We are one of the most watched societies on the planet."