The trail stretches from volcanic South Pacific islands through the Indian subcontinent to a grimy former warehouse district south of the River Clyde.

It connects a discredited online "university" with immigration agents in India and Pakistan who sign up students for private colleges in Glasgow.

The reason for concern is twofold: the qualifications are questionable; and the immigration loophole could allow people of dubious character entry to the UK posing as genuine students.

As a result of The Herald's investigation into the unregulated and burgeoning private college industry in Scotland, the Border and Immigration Agency is checking credentials of some institutions.

Two of these in Glasgow - Great Regent College and Commonwealth College - are affiliated with the University of Newcastle, an Oregon institution which was declared by state authorities to be operating illegally.

That "university" claims its academic accreditation is granted by a government department in the Wallis and Futuna Islands, about two-thirds of the way from Hawaii to New Zealand in the South Pacific Ocean, where the adult literacy rate is just 50%.

Until last weekend, Commonwealth College in Glasgow was prominently displaying the logo of the University of Newcastle on its website and claiming affiliation to it.

The website also displayed the logos of reputable professional organisations such as the Association of Chartered Certified Accountants and the Chartered Institute of Management Accountants and Edexcel, the UK exams body.

They were removed from the site over the weekend after The Herald revealed the organisations had not given permission for their use. Edexcel confirmed yesterday it threatened legal action over the misuse of its logo.

Umbreen Iqbal, the woman behind Commonwealth College, denied a link with Newcastle, though the college website claimed one until Friday. She said: "When Commonwealth College was formed, it dealt with the University of Newcastle. It doesn't now."

Ms Iqbal admitted yesterday that Commonwealth College engages immigration agents on the subcontinent to recruit students seeking UK entry visas, but she maintained its students were all bona fide.

Ms Iqbal claimed last week that Commonwealth College had been running for two-and-a-half years but records with Companies House show it was set up only last June.

Ms Iqbal, 25, and her father Iqbal Sheikh, 55, both from Jordanhill in Glasgow, set up another college in November 2004, Glasgow City College.

Initially, she denied knowledge of it but when told The Herald had registration documents bearing her signature, she said: "We were going to set it up but it never traded."

She confirmed the Commonwealth College prospectus was withdrawn after it was highlighted that photographs purporting to be of the college campus and Glasgow landmarks showed sites in Brussels and New York. She said: "We are in the process of getting new ones made. We are running a legit college."

The other institution highlighted by The Herald last week was Great Regent College, which, despite boasts on its website of a historic campus, is based up a close in Sauchiehall Street.

It is also linked to the University of Newcastle and thus the Wallis and Futuna Islands. It was set up in March by Javid Akhtar, 26, a Pakistani shop assistant who lives in Kinning Park in Glasgow.

One of its website boasts was that "employers consistently marvel how GRC graduates are able to hit the ground running", even though it has yet to open its doors.

Wasim Hashmi, the college co-ordinator, said: "This must have been some mistakes in writing and compiling data."

Of the withdrawal from the website of the 141 undergraduate courses, including philosophy, clinical genetics and mathematics, he said: "We are not ready to offer these kind of courses yet."