Public sector union Unison claims the government intends to go ahead with the privatisation of primary care services.
There is a difference of opinion about NHS private input
In June the Department of Health pulled an advertisement asking private firms to tender for key roles in health care management across Primary Care Trusts.
A new ad has now been published in the Official Journal of the European Union, and Unison says it could lead to firms taking over "a huge range of services".
Health Minister Andy Burnham said it was about securing "quality support".
'Best possible advice'
Local health managers at primary care trusts (PCTs) currently buy in services, although in some areas it has been devolved to GPs.
The government says it is only looking for firms to provide expert advice to PCTs and it would be up to local officials to decide if they wanted to use that private expertise.
"If they're able to use the best possible advice and support available from around the world to do that job, then certainly as a health minister, I want them to have access to that high quality support," Mr Burnham told the BBC Radio 4 Today programme.
Last month, Health Minister Lord Warner withdrew an earlier form of the notice from an EU journal when it provoked uproar from unions.
He said that a drafting error had been responsible for the mistaken impression that clinical services were up for tender.
But according to Unison the new advertisement shows "very, very little difference" with the last one.
"It's very clear that this new advert is inviting organisations to provide a huge range of management, health and support services across PCTs," Unison's head of health, Karen Jennings, told the Today programme.
She said other unions and professional organisations shared Unison's concern.
"This advert not only enables PCTs to continue to outsource commissioning responsibility, but it's also so unspecified and open-ended in its nature, it is effectively allowing outsourcing to take place on the widest possible scale," she said.
"So, for example, a private firm could come in and start to commission for other services for the NHS."
But Mr Burnham denied that the private firms were being brought in to decide what services were offered on the NHS.
"They (PCTs) are publicly accountable for the services they commission on behalf of their local population - and that will not change."