The Business and Technology Education Council's awarding body is investigating how certificates came to be issued early over three years for 800 students at Derby College, Wilmorton. Some were claimed by the college 18 months before students qualified.
Though there is no suggestion of fraud at Derby College, the Further Education Funding Council is understood to be concerned that the system may be being deliberately abused elsewhere in the sector.
The inquiry comes just three weeks after an investigation was launched into allegations that Sight and Sound College in Greenwich, south London had falsely claimed students had passed vocational courses.
All the students involved in the Derby case were training on BTEC courses to become vocational qualification assessors. A member of staff is understood to have ordered their certificates as soon as they enrolled rather than when they qualified to avoid delays by BTEC in issuing certificates.
Though the quality of the training they received is understood not to be questioned, and none actually received certificates until internal verifiers confirmed they had been properly assessed, the irregularities in the way awards were claimed could mean the college will have to reassess all records.
BTEC will have to rule on the implications of its inquiry findings for validity of the hundreds of NVQs subsequently assessed by the individuals involved. Evidence that certificates can be obtained prematurely - with no proof individuals have reached the required standards - could damage vocational qualifications' validity.
BTEC, which confirmed an investigation is taking place but declined to comment further, will have to examine how its own external moderation mechanisms - designed to monitor quality control - failed to pick up the dates' inconsistencies.
Derby College, which has had its right to award the certificates suspended by BTEC, conducted its own inquiry when it was alerted to the problem. A member of staff has been suspended on full pay.
The incident is a fresh blow for the college, recovering under a new regime following a corruption investigation two years ago.
However, the Further Education Funding Council has moved swiftly to defend its recent record under principal David Croll, appointed last July. A spokeswoman said: "The college independently became aware something was amiss and immediately acted to deal with an administrative problem dating back several years."
Mr Croll said the college was working with BTEC to identify action needed. He added: "All of the BTEC moderation reports that have been made over the past few years have indicated that the quality of the student work is of an exceptionally high standard."
The problem was discovered last autumn, when a student alerted the National Council for Vocational Qualifications.
Governors at Derby, handpicked by Education and Employment Secretary Gillian Shephard following the Shattock inquiry, are understood to be deeply concerned that they were not told of the problem immediately by the NCVQ, in the light of the college's high national profile. The NCVQ said it had fulfilled its obligations by asking BTEC to investigate.