Nurses can they are forced to move patients around
Patients in A&E units are being put at risk because people are being admitted to inappropriate wards so hospitals can hit the four-hour target, nurses say.
A poll of 500 emergency nurses found three-quarters were regularly pressured to admit patients to the wrong wards sometimes for as little as 30 minutes.
Patients needing surgery had been put on gynaecology or orthopaedic wards, said the Royal College of Nursing.
But the government said the target had improved patient care.
The college is calling on ministers to relax the target so that only 95% of patients need to be seen within four hours to give health staff more flexibility.
The target was originally set at 100% in 2000, but was reduced to 98% three years later amid concerns, particularly from doctors, that it was too restrictive.
But the college's survey suggested staff were still being forced to move patients around the system.
Speaking at the nurses' annual conference in Bournemouth, RCN general secretary Peter Carter said patients were put in wards that were "a bit like a staging post".
As well as gynaecology and orthopaedic wards, he said this could include medical assessment units, generally used for triaging, and observation units.
"The point is that because of pressure from the government and this four-hour target is seen as such a critical issue, people are going to inappropriate places. It is not good for care and causes confusion."
Rabina Tindale, a senior lead A&E nurse and head of the RCN's emergency care association, said it was worse at peak times.
She said she had heard of stroke patients being admitted to medical assessment unit.
"Although the nurses can care for them, they do not have that specialist experience."
She added the RCN was now calling for a 3% reduction in the target to take the "pressure out of the system".
She added: "Although nothing catastrophic has been reported, we don't want to wait for that to happen."
Lib Dem health spokesman Norman Lamb said: "Targets must not be allowed to override the common sense and good judgement of staff.
"If the government insists on prioritising central targets at all cost, it risks alienating staff and compromising patient care."
But a Department of Health spokeswoman said the target had been a force for good.
"Long waits at A&E, like those we used to see, are unacceptable to the public.
"It is a huge tribute to NHS staff that the vast majority of hospitals now regularly meet the target."
And she added patient care was paramount and that was why the target was not for 100% of patients.
Meanwhile, in his opening speech at the conference, Mr Carter said nurses were being hampered in doing their job, citing staff shortages, mixed-sex wards and high rates of bed occupancy.
"There are just too many obstacles to delivering the kind of care you want to as skilled professionals."
He also called for a debate about the issue of presumed consent for organ donation.
The government has indicated it is in favour of swapping the opting in system currently in operation for opting out in a bid to boost the number of organ donors - although no decision has yet been taken.
It came after nurses at the conference rejected a motion which called for the RCN to oppose attempts to introduce presumed consent.