Labour denied a proposed new election poster campaign was anti-semitic, after it transposed the heads of Michael Howard and Oliver Letwin - who are both Jewish - on to pigs.

The ad, which is supposed to play on the idea "pigs might fly", bears the caption "The day the tory sums ad up", features both the leader of the opposition and the shadow chancellor as pigs with wings.

Andrew Mennear, the Tory candidate for the constituency of Finchley and Golders Green, which has a large Jewish population, demanded an apology and that the Trevor Beattie-designed poster be withdrawn, calling it "shocking and tasteless".

He said: "I am shocked the Labour party finds it remotely clever or amusing to impose the faces of probably the two highest profile Jewish politicians on to flying pigs."

However, neither Tory high command nor the Board of Deputies of British Jews wanted to get involved in the row. A spokesman for Conservative central office said "We have no comment whatsoever to make", while the Evening Standard quoted an unnamed source within the board as saying the posters "really aren't the wisest things we've ever seen" but there was no official reaction.

The design is one of several Labour party members are currently on voting on in a website survey. A party spokesman denied the poster was "in any way" anti-semitic.

He said: "We reject absolutely suggestions that this poster is in any way anti-semitic. What it certainly is, is anti-Tory."

However, the row does come at a sensitive time, with the world yesterday commemorating the 60th anniversary of the liberation of Auschwitz yesterday, an event attended by the foreign secretary Jack Straw and Europe minister Denis MacShane.

Mr Blair warned yesterday that the Holocaust did not begin with the gas chambers but "with a brick through the window of a Jewish business, desecration of a synagogue, the shout of racist abuse in the street".

The flying pigs posters is the lead option given to Labour members on the party website, in a poll which will see the winner go up on thousands of poster sites nationwide.

The designer, Mr Beattie, is an old Labour favourite, and will be in charge of election publicity.