The DUP has not directly addressed claims it fines its political representatives if they talk to the media without permission.
A party source told the BBC's Nolan Show politicians must pay up to £1,000 if they break internal rules on dealing with the press.
The source also claimed the party was boycotting the radio show over its coverage of the Renewable Heat Incentive scandal.
While the party declined to comment on the claims, it said its chief executive, Timothy Johnston, does write to members about their conduct "from time to time".
In a statement, the DUP said it operated under a constitution and a code of conduct, passed by its executive.
"The chief executive, on behalf of the party officers, writes to members on code of conduct matters, as he is required to do from time to time," a spokesman said.
"The party does not comment on its internal procedures."
The statement added: "The party reserves the right to decide what programmes to participate in and the best mix of platforms to ensure ongoing communication with the people of Northern Ireland".
The BBC reported it had seen a letter signed by Mr Johnston imposing a £100 fine on an elected representative.
The broadcaster said it understood politicians who repeatedly break party rules on speaking to the media face fines of up to £1,000.
The other Stormont parties told the BBC they did not fine their members.
