Health Secretary Alan Johnson says he wants to see doctors take a lead in tackling the sick-note culture.
He has urged GPs to issue "well notes" setting out what tasks a worker can perform instead of certificates automatically signing them off.
And he has encouraged employers to run health clinics in a bid to cut the estimated 175m working days lost to sickness each year, at a cost of £13bn.
But doctors' leaders said GPs should not be used to "police the system".
They said if GPs were brought in to play such a proactive role it could damage the doctor-patient relationship.
Mr Johnson, whose department is responsible for health in England, is due to give a speech to the British Heart Foundation on Wednesday.
He said firms such as British Gas and Parcelforce have seen reduced sickness rates after running advice sessions to manage back pain and mental health problems.
But it is the changes to the GP sick certificate, to be piloted in the summer, which are proving most controversial.
Along with these changes, GPs will also be expected to offer patients advice about what they can do to get fit for work.
The announcements come ahead of a publication in March of a report by Dame Carol Black, the national director for health and work, who is looking at the issue.
The "sick-note culture" is also seen as the gateway to incapacity benefit.
GPs are responsible for signing people off for the first six months, before they are formally passed on to the centrally-administered incapacity benefits system.
The UK has one of the highest proportion of people on incapacity benefit in Europe after numbers have more than trebled since the 1970s to 2.7m.
HAVE YOUR SAY
Of course GPs should take responsibility for ensuring that only people who are genuinely ill are signed off as 'sick'
The system is due to be reformed later this year when claimants will be expected to take part in programmes aimed at getting them back into work.
Mr Johnson said the evidence showed that far from being bad for health, work is generally good for people's health.
He said: "We are not asking GPs to police the benefits system and we are not suggesting that GPs shouldn't sign sick notes."
He said too many people ended up drifting on to incapacity benefit via the sick note system.
"If we can stop that and help people back into work that is a good thing. That is what we are trying to do and I don't think the current sick note system helps with that."
But Dr Peter Holden, of the BMA's GPs committee, says: "GPs are often placed in a difficult position between their patients and the system when issuing sick notes in the early stages of illness.
"Confirming that a patient is unwell is very different from making a judgement on whether someone is well enough to do their job.
"This may be determined by a host of other non-medical factors concerning the equipment they are using or the physical environment in which they work. GPs should not be there to police the system."
The TUC said the proposals appeared to be a "missed opportunity".
A spokesman said the government should focus on making the system more flexible for people to return to work gradually without losing all their benefits straight away.
It also called for improvements to rehabilitation services and more investment in preventing people becoming ill in the first place.