Cigarettes could be sold only in plain brown packs within months, after a U-turn by the Tory-Lib Dem government at Westminster.

The surprise announcement came as ministers were pressed on the issue by Glasgow Labour MP Ann McKenchin.

The change in the law would make brightly coloured and stylishly designed packs illegal.

Instead, all cigarettes would be sold in uniform plain packs carrying large picture health warnings.

Campaigners have been calling for the move which they say will make cigarettes less attractive to young people.

But there has been criticism that plain packs would be a step too far towards a "nanny state".

Last February MSPs unanimously backed a motion at Holyrood to allow any future legislation on plain packaging brought in by the UK Government to apply north of the Border too.

But David Cameron's government has been accused of dragging its feet n the issue, amid accusations of pressure from tobacco firms.

Mr Cameron had appeared to kick the idea into the long grass in 2013 suggesting that more evidence was needed.

But Public Health Minister Jane Ellison has announced that MPs will vote on the issue within weeks, with a view to bringing the legislation into force by May 2016.

She said: "We cannot be complacent. We all know the damage smoking does to health.

"This Government is completely committed to protecting children from the harm that tobacco causes."

Ms McKechin welcomed the U-turn saying: "I'm delighted that the government accepted my call to move forward on an issue which they have been postponing for three years".

"Clearly the embarrassment factor was becoming too much".

The move was also welcomed by Cancer Research UK who released figures showing that almost three quarters, 72 per cent, of voters across the political spectrum said they supported the move.

Harpal Kumar, Cancer Research UK's chief executive, said: "We applaud the Government for taking this big step towards getting plain, standardised cigarette packs on the shelves and protecting children from tobacco marketing."

But Tory backbench MP Philip Davies condemned what he said was "a triumph for the nanny state".

The legislation is expected to pass even though MPs will be given a free vote on the i9ssue.