THREE of Scotland's leading universities have resigned their membership of the CBI, arguing its decision to become a registered campaigner on the No side in the referendum fight is at odds with their political neutrality.

Glasgow, Aberdeen and Edinburgh universities felt it inappropriate to belong to, and help fund, an organisation that will be allowed to spend up to £150,000 in the 16-week "regulated period" before polling day on communicating its view that remaining in the UK is in the best interests of the Scottish economy.

Another university, Glasgow Caledonian, will take a decision on its continued membership today. A fifth, Aberdeen's Robert Gordon University, has expressed its disapproval of CBI Scotland's move but chosen not to resign, saying its membership was about developing business links and not the issue of independence.

CBI Scotland's decision has placed the country's universities in a difficult position. They are right to consider their political impartiality and guard it jealously. It may be they are also conscious of the degree to which they rely on funding from the Scottish Government. It came as no surprise when government agencies VisitScotland and Scottish Enterprise quit the CBI - ministers made it plain membership was "inappropriate" for them - and the wider Yes campaign yesterday went further, claiming no body in receipt of public funds should remain part of the organisation. The pressure is clearly on.

For its part, the CBI has expressed regret at the universities' departure and sought to reassure other members that it will not become engaged in a door-knocking, leaflet-posting, election-style campaign in the run-up to the referendum. Rather, argued director general John Cridland, the organisation needs to ensure it complies with Electoral Commission rules when it presents its very clear opposition to independence to businesses and in press releases.

The key test for CBI Scotland will be how its majority of private-sector members react. So far three companies are known to have resigned over the issue. STV is bound by strict broadcasting rules. The second, Balhousie Care Group, is chaired by a prominent figure in the Yes campaign while the other, pioneering wave energy firm Aquamarine Power, happens to be the recipient of substantial support from Scottish Enterprise. Other members are supportive, CBI Scotland officials insist privately. They received a large number of emails from chief executives backing their decision over the weekend, they claim, though they are frustrated no-one has made their backing public.

If firms do agree, it's perhaps time they came out and said so. The desire of a commercial enterprise not to alienate customers is understandable, especially in the light of the recent social media campaign to boycott a travel firm whose founder warned against independence. However, if bosses are genuinely concerned about impact of a Yes vote on their business, silence may be a luxury they cannot afford as the race becomes ever tighter.