A Scottish Government check of college waiting lists launched last year found an estimated 5800 people could not find a place. But Scottish Labour claimed the actual figure could be more than 13,000.
The audit was carried out after FE colleges warned they were turning many potential students away because of cuts to courses and staff.
Officials pointed to waiting lists held by colleges at the time which had more than 20,000 names on them.
Scotland's colleges argued the lists – while not representing the number of individual learners – were an indication of unmet demand.
However, this was dismissed by Michael Russell, the Scottish Education Secretary, although he agreed to an audit of the figures.
John Henderson, chief executive of Colleges Scotland, which represents the sector, welcomed the interim findings of the report, compiled by the Scottish Funding Council (SFC).
He said: "We surveyed our member colleges last September and estimated the numbers on waiting lists for courses in Scottish colleges at around 20,000.
"If the Scottish Government provides clear guidance on how it wishes waiting list numbers to be reported by colleges, we will work with our members to implement it rapidly.
"We can then provide updated, Scotland-wide numbers the Government can use to assess the unmet demand for college places."
Hugh Henry, for the Scottish Labour Party, said the number of people who could not find a place at college could be as high as 13,000, with the audit discounting those who had gone back to school or no longer wanted a place for other reasons.
He said: "If these figures are repeated across Scotland then it still looks likely more than 13,000 Scots were denied a place at college at a time of record high youth unemployment. Mr Russell tried to rubbish the figures, but this even report indicates many Scots are being denied a college place."
However, the Scottish Government said the audit showed previous estimates were wildly inaccurate.
And a Government spokesman stressed that, since last summer, many of those on waiting lists were no longer interested in a college place.
"In the one college where the audit is fully complete, including further follow-up, fewer than 5% of the people reported on the waiting list are waiting for a place at college.
"The full report of the audit will be published in February."
The initial analysis by the SFC found that only 9% of the combined waiting lists were duplicate records, while 25% had enrolled at another college. In addition, 38% had now indicated they no longer wanted to go to college leaving some 28% unable to find a place.
The row over waiting lists came at a difficult time for further education in Scotland with cuts to the teaching budget and thousands of job losses.
The Scottish Government is also seeking to reorganise the sector along regional lines with mergers of colleges across the country and new regional boards to run them.