Sinn Fein president Gerry Adams has insisted that allegations of IRA spying at Stormont will not undermine the peace process, following the latest arrest.

Police investigating IRA intelligence gathering are still questioning the civil servant arrested on Wednesday, who had access to the office of the former first minister, David Trimble.

He was arrested after a security operation in Belfast which included searches at Castle Buildings at Stormont.

It is understood he had access to ministers' diaries.

Gerry Adams: "Focus has been on one side of things"

Speaking to reporters after giving an address to Irish Americans in New York on Thursday night, the Sinn Fein leader again denied that any member of his party was involved in spying.

He claimed the police investigation was being used as a smokescreen to hide others' failings in the peace process.

"People know that this is a process of change, they know that there is resistance to that change and they know that it is going to take time to sort all of these matters out," he said.

"They wonder why there is a focus on only one side of things and what are merely claims and allegations."

Mr Adams has been in New York and Washington giving briefings on the state of the political process and he met President Bush's Northern Ireland adviser Richard Haass earlier this week.

Meanwhile, speaking in Belfast, his party colleague Conor Murphy said there was a growing belief that there was a witch-hunt against Catholic civil servants.

"Many people are now considering there is some form of a McCarthy-type witch hunt against Catholic civil servants who happen to live in nationalist working class areas," he said.

'Political implications'

Mr Trimble has said the arrest is "a most concerning and serious development and appears to have huge implications for the political process".

He said the arrested man had access to "sensitive" information.

David Trimble said arrest could have serious political implications

Prime Minister Tony Blair's spokesman said the allegations were "serious and disturbing".

The arrested man also had access to the office of SDLP leader Mark Durkan, the former deputy first minister at Stormont.

He added: "I would caution against any rush to judgment in this matter and would ask that the media respect the privacy of the civil servant concerned."

The development came a day after Northern Ireland Secretary Paul Murphy announced that the government was to convene all-party talks aimed at reinstating the political institutions.

Mr Murphy and Irish Foreign Minister Brian Cowen have been meeting leaders of the parties separately over the last few days.

Mr Cowen said the latest allegations put new strain on the political process.

"These are very serious matters and what they are doing, issues like this, is undermining confidence and trust in the process," he said.

Northern Ireland's power-sharing executive was suspended on 14 October amid allegations of IRA spying within the Northern Ireland Office.

Four people, including Denis Donaldson, head of Sinn Fein's administration at the Northern Ireland Assembly, were charged last month after police seized documents in raids on republican homes.