Khalifah al-Akili emailed the Guardian shortly before his arrest to say he thought he was the target of an 'entrapment' sting

The arrest of a Pittsburgh man described as a Taliban sympathiser has sparked allegations that the FBI deployed a notorious confidential informant used in previous controversial stings on suspected Muslim radicals.

Khalifah al-Akili, 34, was arrested in a police raid on his home on March 15. He was later charged with illegally possessing a gun after having previous felony convictions for drug dealing. However, at his court appearance an FBI agent testified that al-Akili had made radical Islamic statements and that police had uncovered unspecified jihadist literature at his home.

But, in a strange twist, al-Akili's arrest came just days after he had sent out an email to friends and local Muslim civil rights groups complaining that he believed he was the target of an FBI "entrapment" sting. That refers to a controversial FBI tactic of using confidential informants – who often have criminal records or are paid large sums of money – to facilitate "fake" terrorist plots for suspects to invent or carry out.

In the email – which was also sent to the Guardian before al-Akili was arrested – he detailed meeting two men he believed were FBI informants because of the way they talked about radical Islam and appeared to want to get him to make jihadist statements. According to his account, one of them, who called himself Saeed Torres, asked him to buy a gun. Al-Aikili said he refused. The other, who was called Mohammed, offered to help him go to Pakistan for possible Islamic radical training. Al-Akili also refused.

In the email al-Akili recounted that he obtained a phone number from Mohammed and put it into Google. The search returned a reference to the case of the Newburgh Four, where an FBI confidential informant called Shahed Hussain helped secure the convictions of four men for attempting to blow up Jewish targets in the Bronx.

Hussain's actions became notorious among civil rights groups due to the incentives he deployed on his targets, who were local black Muslims in the impoverished town of Newburgh. They included offering one suspect $250,000, a car and a free holiday. Al-Akili said he also found a picture of Shahed Hussain on the internet and realised it was the same man as "Mohammed".

Al-Akili concluded his email by saying: "I would like to pursue a legal action against the FBI due to their continuous harassment and attempts to set me up." The Guardian contacted al-Akili by email and on March 14 by phone and al-Akili agreed to talk more to the Guardian about his belief that he was being set up by Hussain. But he was arrested the next day and has been denied bail as a potential threat to the public, keeping him in jail.

Al-Akili's lawyer Mike Healey believes that the FBI may have been monitoring al-Akili's emails, and possibly his phone, and then rushed to arrest him once Hussain had been identified and al-Akili had effectively gone public with his fears.

Healey questioned why the FBI would use Hussain, who has also been widely criticised for his role in another "entrapment" case in Albany, New York, which resulted in the jailing of a local imam and a pizza shop owner. "What are they doing bringing him here? I am amazed they would use someone like that," he said.

Yet, despite being painted in court as a dangerous radical Islamist, the only charges brought against al-Akili were for firing a rifle – which Healey said was owned by a friend – at a local shooting range almost two years ago in June 2010. Al-Akili faces the prospect of a hefty jail sentence if found guilty.

A spokesman for the FBI declined to comment on whether the agency had been using Shahed Hussain as a confidential informant in Pittsburgh.