WHITEHALL'S next line of attack on the SNP Government's plans for independence will be on Europe, with a new analysis paper due out later this month.

Danny Alexander, the Chief Secretary to the Treasury, is expected to front the forthcoming document in the UK Government series, seeking to expose holes in the Scottish Government's White Paper with regard to an independent Scotland's desired membership of the EU and other international bodies such as Nato.

It is also understood that the Home Office is drawing up an analysis paper on security, borders and passports.

Elsewhere, Downing Street has indicated that David Cameron is not planning to increase his referendum activity in any significant way ahead of the September poll. At the weekend, the Prime Minister made clear he would "work very hard to play my part"for the pro-UK campaign.

Asked, given the importance of the next few months, whether or not Mr Cameron would be making more speeches about Scottish independence and visiting Scotland more, his spokesman replied he will visit all parts of the UK, including Scotland."

Last month, Alistair Carmichael, the Scottish Secretary, forcefully denied his Cabinet colleague was a "back-seat driver", stressing how Mr Cameron was "completely engaged" and described his approach as "absolutely right and appropriate".

It is believed the PM will chair a session of the UK Cabinet in Scotland sometime in the spring.

The Downing Street 2014 grid has been outlined for most of the year, with key referendum events pencilled in but it unclear just how involved Mr Cameron will become later on.

At present, Whitehall sources appear content with the Prime Minister's low-key strategy given the opinion polls continue to show a healthy lead for the No campaign. This is the main reason why Mr Cameron has refused First Minister Alex Salmond's invitation to a live TV head to head debate. Pro-Union strategists believe the Tory leader will have more to lose than to gain; the situation would only change if there was a significant deterioration in the No camp's fortunes.

It is thought one of developments in the coming weeks will be the launch of a "stick with us" campaign from people south of the Border, which could include a range of celebrities, extolling the virtues of the social union between Scotland and England.