Labour-supporting Liz Dawn is best known as Vera Duckworth
The Labour Party broke privacy rules by making automated phone calls to nearly 500,000 people without their consent, the information watchdog has ruled.
In 2007 it was told not to use a recorded message by actress Liz Dawn, best known as Coronation Street battleaxe Vera Duckworth.
But more complaints were made in 2009 - an enforcement notice has been served on the party to stop the calls.
Labour said it would examine the ruling and always tried to meet guidelines.
The commissioner's office said Labour had breached privacy and electronic communication regulations that ban automated direct marketing calls to anyone who has not consented to receive them.
Labour has 28 days to appeal - failing to comply with an enforcement notice could lead to a prosecution.
The party is not the first to fall foul of the rules on automated phone calls - nicknamed "robocalls" in the United States.
The Conservatives, Liberal Democrats and Scottish National Party (SNP) have all had similar notices served.
The SNP, which had been criticised over its own automated calls using the voice of Sir Sean Connery, made one of the complaints against Labour in 2009.
Labour - having been warned in 2007 that calls featuring Liz Dawn's voice amounted to direct marketing - went on to make automated calls featuring her voice in 2009.
The calls were made to about 495,000 people in areas with strong Labour support, urging them to vote in local and European elections.
Deputy information commissioner David Smith said all the major parties had been told that any promotion counted as direct marketing.
He added: "The fact that the calls were targeted at what were believed to be Labour-supporting areas confirmed our view that they were designed to promote the Labour Party's electoral cause by encouraging Labour supporters to vote."
The Labour Party said it had considered advice from the information commissioner's office before making the calls and had believed it had abided by it.
A spokesman said: "We will now examine this decision in detail. The Labour Party has always sought to abide by the Information Commission guidelines and will continue to do so in the future."
But the SNP complained that it had taken the information watchdog too long to act.
It said the Conservatives, SNP and Lib Dems had faced immediate enforcement notices but the watchdog appeared to have "relied on a promise of good behaviour" from Labour in 2007.
Joe Fitzpatrick, the MSP who lodged a complaint in 2009, said: "Labour have been the subject of repeated complaints over their inappropriate use of telephone calls during election campaigns but it seems where other parties have faced the law Labour have been allowed to get away with it."
Liz Dawn, a longstanding Labour Party supporter, left Coronation Street in 2008 after 34 years of playing Vera Duckworth, one of the ITV1 soap opera's most popular characters.