A former White House aide, two arms merchants and three associates of fund-raiser Carl R. (Spitz) Channell have been granted limited immunity to answer congressional questions about the Iran-contra affair.

U.S. District Court Judge Thomas Hogan granted limited immunity to the six potential witnesses yesterday, officials said.

They are expected to be called to Capitol Hill this week to give depositions. The six had refused to testify under oath without limited immunity, which prevents them from being prosecuted based solely on what they say under congressional questioning.

Immunity was granted 10 days after it was requested by the select congressional committees.

Subpoenas were to be issued immediately, House committee spokesman Robert Havel said.

Channell and his partner, Richard Miller, are the only people to be indicted so far in the the scandal. The two pleaded guilty to conspiracy to defraud the government after they were accused of illegally raising money for the contras while U.S. aid was banned.

Those to be forced to testify include Johnathan Miller, a fired White House aide associated with contra courier Robert Owen; three Channell associates, Cliff Smith, Chris Littledale and Frank Gomez; arms dealer Jim Atwood; and David Walker, a British citizen linked to counterterrorism work.