The Information Commissioner's Office is investigating whether Labour has overstepped the mark on telemarketing. If the party is found guilty, it could be barred from repeating the activity and fined 拢5,000.
The phone calls use an automated voice system to ask people which party they intend to vote for in the election, inviting them to press their keypad to respond. The information gathered enables the campaign managers to send out direct mail, which encourages those who answer Labour to use their postal vote and presents those who answer otherwise with reasons to vote Labour.
The ICO is acting on at least 680 complaints passed on to it by the Liberal Democrats from members of the public who are registered with the Telephone Preference Service not to receive marketing calls without permission.
Matthew Taylor, chairman of the Liberal Democrats, told the Evening Standard: "Labour is acting no better than a crooked double-glazing salesman. This seems yet another dirty trick."
Labour's defence is that it is not marketing or selling the party but only gathering information about people's voting intentions.
A Labour spokesman said: "We've had legal advice that everything we do is within the law."
The Liberal Democrats say that in not calling TPS registrants they are conforming with advice given out by the ICO.
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