Northern and Shell's newspaper price cuts are being extended to the Daily Express.
The weekday and weekend prices of the Daily Star newspaper was halved in October.
And now the Saturday price of the Daily Express is beng cut from 85p to 45p, according to NFRN, the newsagents trade body.
The body also said it has been informed that, from Monday 28 December, the weekday price of the Scottish Daily Express is being reduced from 50p to 30p. Last month, the Daily Express's average circulation in Scotland was 40,564, around 10 per cent of its total.
The NFRN, which said the price cuts are being run until further notice, has condemned the move. It said that the sale of the Saturday edition will need to increase by 89-90 per cent for retailers to receive the same margin as before.
Chief executive Paul Baxter suggested ABC figures for the Star showed cutting its price did not make sense.
The Star's cover price was halved on 5 October. In the full ABC month before this change, the newspaper recorded an average circulation of 403,380. Last month, the first full month since the cut, saw its circulation increase to 450,045.
He said: “The reality is that loyal readers happily paying the full price have got a good deal but his product has been badly devalued and the category continues to slide away. We are, therefore, aghast that Richard Desmond has decided to drop the cover prices on the Scottish and Saturday editions of the Express.”
NFRN national president Ralph Patel said: “There is no credible justification for such moves, especially given the fact that both The Sun and Mirror failed to follow suit when the price of the Star was halved. Rather than injecting the promised excitement and long overdue extra sales into the newspaper category it appears that Richard Desmond is hell bent on ruining an industry that has helped earn him millions.
“As a result, the NFRN will be reminding our members that they have choice in what they stock, that they should review the space they give to products that do not deliver the profits needed to run successful businesses and that they should focus on giving display and support to the titles that support them.“