Gordon Brown was last night at odds with Jack McConnell by stating Forth road bridge rises had been scrapped, openly contradicting the Scottish Executive over the politically explosive subject.

Ministers yesterday deferred a decision on whether to back the rises, from GBP1 to up to GBP4 per car. The move was widely seen as a short-term political fix to avoid backing higher charges before the Dunfermline and West Fife by-election, expected on February 9. However, the chancellor, who holds the neighbouring Kirkcaldy and Cowdenbeath seat, suggested the rises had been abandoned altogether. "I welcome the decision to abandon these increases, " he said last night in a statement.

Sources close to Mr Brown denied he was trying to "bounce" the executive. "It is our understanding that the proposed increase has been abandoned." Allies of the chancellor said he had concluded the charges were being scrapped after an "interpretation" of the executive's reasons for delay. "It may be an interpretation, but it's our interpretation."

Aspokesman for the first minister insisted a decision had merely been delayed until late February or March, after ministers studied reports on the bridge's condition and whether there should be a second road bridge across the Forth. Asked about the chancellor's statement, the spokesman said: "I'm not sure why (Mr Brown) would say that. Perhaps something has been lost in translation."

Alex Salmond, SNP leader, said the chancellor was trying to hoodwink the public.

"Gordon Brown may try to pull the wool over the eyes of the people of Fife, but it simply won't wash. The main reason for postponing the announcement is that it's bad news for Labour and bad news for the Liberal Democrats."

The rise has been suggested as a way of cutting congestion.

Labour is defending a majority of 11,562 over the LibDems in the by-election, called after the death of Rachel Squire MP.