Scotland's ministers are coming under increasing pressure to subsidise lifeline air routes in the Highlands and Islands.

Members of Highland Council are concerned that fares - which are said to be the highest in Europe - are driving customers away and threatening the viability of "vital air services".

They have been told that the number of passengers using scheduled air services in the area has plummeted by a third in the last four years.

This is despite a �12m a year subsidy to Highlands and Islands Airports Ltd, which says it has improved the infrastructure on the ground but cannot underwrite fares for travellers.

European funds

Western Isles councillors have already urged the Scottish Executive to do more to support air services.

They say few travellers, apart from local authority and civil service staff, can now afford to fly.

One suggestion to be put forward on Thursday is for more routes to be included under the Public Service Obligation Scheme which uses European Funds to subsidise lifeline services.

In March this year Chancellor Gordon Brown announced in his Budget that he would abolish air passenger duty for flights from Highlands and Islands airports.

That move was welcomed by the Inverness Chamber of Commerce and the Scottish Council Development and Industry, which lobbied the Scottish Parliament to take action on fares on behalf of the area's social and business communities.