A Sri Lankan doctor who admitted aiding the South Asian nation's Tamil Tiger separatist group began his appeal on Tuesday to be allowed to resume work in Britain.
Murugesu Vinayagamoorthy spent almost five years in a US jail for providing material support to the rebels, who were defeated by Sri Lankan troops in 2009 after decades spent fighting for an independent homeland.
The 62-year-old doctor was released last year and has asked Britain's General Medical Council (GMC) if he can see patients again at the clinic he runs with his wife in Enfield, north London.
But at a disciplinary hearing, the GMC, which registers doctors to practise in Britain, said Vinayagamoorthy's links to the LTTE (Liberation Tigers of Tamil Eelam) had "stepped wildly beyond any reasonable boundary."
"The conviction is a conviction of a serious offence," GMC lawyer Charles Garside said on the first day of a three-day hearing in Manchester, northwest England.
"The doctor practises in London, a very multi-racial city including Sinhalese and Tamil people," he said, referring to Sri Lanka's two biggest ethnic groups.
"A substantial number of people would feel unease at consulting a doctor who was convicted of offences in relation to terrorism."
The LTTE is listed as a terrorist organisation by the European Union and Canada, as well as the United States.
The GMC heard that undercover US agents, posing as State Department officials, had taped the doctor attempting to bribe them into removing the LTTE from the United States' list of terrorist organisations.
Vinayagamoorthy was also recorded expressing support for suicide bombings and the use of child soldiers.
The doctor denies being a member of the Tamil Tigers or raising funds for them, but has admitted "stupidness" in getting involved in the situation that led to his imprisonment.
He was arrested in the United States in August 2006 and remained in custody until his sentencing in April 2011, when he received a jail term equivalent to the time he had already served, and was released.
The LTTE, founded in 1976, fought for an independent state for Tamils in northern Sri Lanka until the rebels' defeat in 2009.
The United Nations estimates some 100,000 people perished during the 37-year ethnic conflict.
A Sri Lankan government inquiry cleared the military last week of deliberately targeting civilians in the final stages of the civil war.