Education chiefs this week will be forced to reveal to what extent Birmingham's GCSE results were achieved by taking poor pupils off their roll before the exams.
The authority has come under fire after The Birmingham Post last year revealed two schools praised for turning around attainment removed 62 pupils between them.
The youngsters, thought unlikely to achieve good results, were referred elsewhere before a January audit and were not included in league table results.
Before Christmas, Birmingham's education scrutiny committee ordered the authority to reveal how many pupils were removed from Year 11 prior to GCSE exams.
They also demanded to know what alternative provision was provided for the children and what qualifications, if any, they obtained.
Findings of the inquiry are due to be presented to the committee on Wednesday.
Coun Jon Hunt (Lib Dem Perry Barr) said: "We want to know more about this. There are some questions about how the city's GCSE statistics add up.
"If pupils are taken off roll and are sent to a further education college, for example, they don't appear anywhere in league tables.
"It is an anomaly because it means there is no tracking of them." Coun Hunt expressed concern that schools may be removing problem children so as not to lower their league table position.
"The real issue is whether these young people are getting the best education or if they are being made victims of league tablelitus, if they are being moved from pillar to post for league tables. That is worrying."
Last November education chiefs praised the achievement of Kings Norton High where the pass rate for pupils gaining at least five GCSEs graded C or above more than tripled from 16 per cent to 50 per cent.
A similar achievement was applauded at The College High School in Erdington where the proportion rose from 12 per cent to 34 per cent.
However, investigations by The Post revealed Kings Norton High had taken 36 Year 11 pupils off roll between September 2004 and January 2005.
And at The College High, 26 pupils were taken off roll during the same period.
Scrutiny committee member Coun Jan Drinkwater (Lab Weoley) said: "My concern is that we will have youngsters who will be lost to the system and whether the city has the capacity to manage and organise the alternative provision for these youngsters who are taken off roll."
Coun Drinkwater said it was vital to track what happened to such youngsters and questioned the authority's record achievement for GCSE results.
"I have a real fear that these are youngsters that we are losing from the system," she said.
"They are disappearing because as far as I know they are not included in any of Birmingham's statistics.
"The 56.7 per cent pass rate A to Cs achieved last year would not have included any of the youngsters taken off roll. As far as I am concerned that has the effect of possibly artificially inflating Birmingham's result."
Of the 36 pupils eligible for GCSEs who were removed off roll at Kings Norton High, 28 were referred on to colleges for alternative educational provision.
Five moved out of the area, two were "untraceable" and one was permanently excluded.
At The College High, 14 were moved into alternative provision and 12 permanently excluded.