A Hertfordshire recruitment agency boss says she was told she could not request "reliable and hard-working" applicants.
Devonwood Recruitment boss Nicole Mamo said the Jobcentre Plus in Thetford, Norfolk, told her such an advert could be "offensive" to unreliable people.
Ms Mamo said: "I started to laugh. I said: 'That's crazy'."
A Department of Work and Pensions (DWP) spokesperson said the advert was worded as Ms Mamo requested online - but did not deny it differed in the Jobcentre.
Ms Mamo's company was advertising for a cleaning job at West Suffolk Hospital.
She said that she told a Jobcentre worker that "hard-working and reliable" were essential words for the advert, but received the reply that those words could not be used as they "may discriminate against the unreliable".
"I'm trying to run a respected agency and can't uphold a good reputation with unreliable people", Ms Mamo said.
A spokesman for the Campaign Against Political Correctness said: "This is absolutely ridiculous. If they can't advertise for what they want then the system is broken."
The Equality and Human Rights Commission said that the advert as Ms Mamo worded it was in "no way" a breach of any discrimination law.
A spokesperson for the DWP said: "Reliability is important to employers, as it is for Jobcentre Plus - and we welcome ads seeking reliable applicants."
The DWP said it could not confirm whether advice not to use the word reliable had been offered.