It must rank as one of the more bizarre by-election tactics of recent times. Labour Cabinet ministers are campaigning in the crucial by-election battle in Glasgow East - but the party does not want anyone to know they are there.

Harriet Harman, the deputy leader and party chair, Des Browne, the Defence and Scotland Secretary, and Douglas Alexander, the International Development Secretary, have all been on the by-election trail in the seat but each went there undercover.

Labour's opponents immediately pounced on the low-profile visits as evidence that the party was fighting shy of exposing its heavyweight campaigners to a critical public. The Scottish National Party suggested that Labour was “playing hide and seek” with the voters.

The ministerial visits last Friday went unnoticed because the media, and even the party's local MPs, were not told. Ms Harman spent around 15 minutes canvassing in two streets in the Mount Vernon area, one of the more prosperous parts of a constituency better known for its levels of deprivation.

Mr Alexander spent some time canvassing in the sprawling Easterhouse housing estate, while Mr Browne spoke to shoppers in a supermarket in the Shettleston area.

Usually, when Cabinet ministers spend time in a constituency during a by-election campaign, the party ensures there is a big media presence with staged photo-opportunities.

A spokesman for Labour yesterday struggled to explain the party's new and rather radical strategy.

“We want to keep the focus on Margaret Curran, Labour's excellent candidate, who is standing up for the East End of Glasgow and we don't want anything to detract from that line”, he said.

He dismissed suggestions from The Times that the move represented an attempt to “protect” Ms Harman and her Cabinet colleagues from the embarrassment of having to confront protesters or angry voters.

“Ministers are coming to the constituency but they are knocking on doors, stuffing envelopes and handing out leaflets. The voters in Glasgow East don't want ministerial photo-calls.”

However, one Labour MP, who did not know of the visits until told of them by The Times, said: “I agree it looks a bit strange. Maybe they realise that Harriet is a bit twee for folk up here and that she would only have annoyed people if they'd known she was here. So they sent her to what you might call a bijou part of the constituency to protect her.

“As far as Des Browne is concerned maybe you would have invited a lot of shouting and bawling about Iraq and Afghanistan by telling people.”

Labour also claimed visits by Cabinet ministers can backfire. The spokesman pointed to the party's experience in Dunfermline and Fife West by-election in early 2006, when the Liberal Democrats pulled off a major shock by taking the seat from Labour.

That campaign featured Gordon Brown, then Chancellor,, and other government ministers and completely overshadowed the party's candidate. Mr Brown will not be visiting.

Other parties reacted with puzzlement and surprise at the Labour decision to keep the visits under wraps.The Scottish National Party suggested that Labour was “playing hide and seek” with the voters.

Angus Robertson, the party's leader at Westminster, said: “Instead of being straight with the voters Labour Ministers are engaged in undercover operations, sneaking in and out when they should be facing up to the public.”

Annabel Goldie, the Scottish Tory leader, said that the tactic showed Labour was “leaderless in Scotland, rudderless in Westminster and spineless in Glasgow East”.

Mr Brown yesterday sidestepped stinging criticism from the Roman Catholic Church in Scotland over the Government's stance on abortion and embryology. Ministers have also been accused of delaying a debate on new fertility laws in an attempt to shore up Labour's vote in the constituency.

Mr Brown, asked whether he feared the churchmen were trying to “hijack” the by-election, said that he did not believe any new issues had been raised.

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