By Jamie McIvor BBC Scotland business staff

The owners of some of Scotland's leading newspapers have been preparing to close the book on potential buyers of the titles.

SMG, which owns The Herald, Sunday Herald and Evening Times set 27 September as the deadline for initial expressions of interest in the newspapers.

SMG has described the decision to sell its newspapers as strategic.

The papers attract regional advertisers while its TV, radio and advertising divisions appeal largely to UK-wide clients.

SMG has significant television interests

The company said the sale has not been forced on it by its heavy debt.

However, the �200m or so which the company hopes the papers would raise will go a long way towards reducing its debt of about �400m.

The Herald is a profitable and prestigious title and a number of groups have said publicly that they are considering bidding.

One is led by the former Daily Mirror chief executive David Montgomery and the venture capitalists 3i.

The Daily Mail has been looking at a bid, as has Guardian Media Group and the local paper publisher Johnston Press.

However there has been concern that the owners of The Scotsman, the Barclay Brothers, could buy the titles.

The Sunday Herald has quickly established itself as a strong and respected rival to Scotland on Sunday but has still to break even

While there has been little love lost between SMG and Scotsman Publications, if the Barclays' offered the most money it would be difficult for SMG to say no.

A merger of The Herald and The Scotsman could well get past the competition authorities if economic factors alone were considered, but would cause outrage across the political spectrum.

The Scottish National Party has argued that Scotland needs a diverse media and not mergers.

The new owner would also have to decide quickly whether to keep the Sunday Herald going.

It has quickly established itself as a strong and respected rival to Scotland on Sunday but has still to break even.

SMG was created six years ago when Scottish Television bought The Herald.

The Sunday Herald has made its mark

A year later Scotland's other main ITV station, Grampian, joined the group.

Since then, it has been busy buying other businesses from the advertising company Pearl and Dean to Virgin Radio.

The sale of the papers raises questions about SMG's future direction. SMG wants to hold on to its TV stations and keep on growing .

It said a single UK-wide ITV company is "neither inevitable or desirable".

But many in media circles still think Scottish and Grampian will end up as part of one giant national ITV company after the new Communications Bill becomes law.

The Bill is likely to free SMG to mount a full takeover bid for Scottish Radio Holdings, in which it already holds a significant stake.

SMG could conceivably end up owning most of Scotland's major commercial broadcasters - but without the newspapers, the shape of the company will be substantially different.