The admission, made in a written reply to an MP, confirms the worst fears of further education colleges that the so-called 16-hour rule - which comes into force on Monday - will be applied inconsistently, driving out thousands of potential students incorrectly told they will forfeit support.
Colleges predict a descent into bureaucratic chaos as they are forced to provide a mass of course detail for every jobless student to prove they are studying for no more than their ration of 16 guided learning hours each week.
The top-level acknowledgement by Employment Service chief executive Mike Fogden that job centres may have issued conflicting advice to colleges comes after ministers issued assurances that anomalies in the present benefits rules for jobless students would be ironed out by the change.
Under the present rule, which puts a 21-hour limit on the hours the unemployed can study, colleges have found their local job centres interpreting the restrictions entirely differently even for students taking the same course.
The 16-hour rule is part of a package of benefits changes including the replacement of Unemployment Benefit and Income Support with the Jobseeker's Allowance.
Their introduction has been dogged by delays, and job centres have been left in the dark about the way the 16-hour-rule should be applied. Guidance on the issue only reached them this week, just days before the limit comes into force.
In his letter sent in the summer to Bradford North MP Terry Rooney, Mr Fogden acknowledges that since benefits offices - which must advise colleges on the rule - have not received the guidance, "it is possible that conflicting information has been given".
The Unemployment Unit, an independent research and campaign group, said the confusion had already caused chaos this term, with colleges finding students were dropping out of courses because they had been denied benefits under the old 21-hour rule.
Meanwhile, confused benefits officials were trying to use the 16-hour rule, which only applies to courses funded by the Further Education Funding Council, to hold back benefits for jobless people taking higher education or European-funded programmes at college.
Some colleges had been equally uninformed, including one in London which had to reprint its entire prospectus because courses were incorrectly labelled as full-time - a designation which means students automatically forfeit benefit because they are not considered available for work.
Dick Evans, principal of Stockport College, said the 16-hour rule could potentially lead to "catastrophe". Students had already dropped out this term after having benefits suspended. He said: "There is a lot of unsettlement and a lot of misinformation. The benefits offices are totally confused."
The college was having to be extra cautious over giving access awards - cash to help hard-up students - in case these also jeopardised benefits, he said.
Dith Banbury, guidance team leader at Lewisham College, south London, predicted "chaos" when the new rule came in. The questionnaire, used to determine whether students were entitled to benefits, had been updated only in the past fortnight, she said, yet local job centres were still working to an earlier version.