NHS trusts were not consulted before the government announced changes to the use of face coverings and visitor policy in English hospitals, the chief executive of NHS Providers has said.
Chris Hopson said trust leaders felt "completely in the dark" about the "significant and complex" changes.
From 15 June, hospital visitors and outpatients must wear face coverings and staff must use surgical masks.
The Department of Health says masks can be provided by the hospital if needed.
A spokeswoman said that, while the public were "strongly urged" to wear a face covering while inside hospitals, no-one would be denied care.
Separately, NHS England has lifted the national suspension on hospital visiting with new guidance for NHS trusts.
The guidance, which states visiting will be subject to the discretion of individual trusts and other NHS bodies, advises measures to support visiting, such as:
- Although only one close family member or important contact can be at a patient's bedside, if social distancing can be maintained, a second additional visitor could be permitted in certain circumstances
- Visitors should be told in advance what to expect when they see the patient and be advised about social distancing, wearing protective kit and hand washing
- Visitors must wear masks or face coverings at all times
- People with coronavirus symptoms should not visit
- Where a face-to-face visit is not practical, then a virtual visit should be supported and arranged
The Department of Health said trusts had all of next week to implement the changes and that it had made NHS England aware of the announcement before it was made public.
But Mr Hopson said the announcement by Health Secretary Matt Hancock on Friday was "rushed out" with "absolutely no notice or consultation" of NHS trust leaders.
He told BBC Radio 4's Today programme: "It's the latest in a long line of announcements that have had a major impact on the way the NHS operates, in which frontline organisations feel they've been left completely in the dark, and they're then expected to make significant and complex operational changes either immediately or with very little notice."
He said trust leaders were worried there was not enough strategy or planning and that it felt like "last minute decisions are being made on the hoof that seem overly influenced by politics and that need to fill the space of the Downing Street press conferences".
The announcement had left many unanswered questions, such as when it was appropriate for staff to wear face masks, the numbers of masks needed and how they would be distributed, he added.
Mr Hopson called for a "proper, sensible forward plan and forward strategy of what we are trying to do, where trusts are given the time and space they need to do complex and difficult things".
Meanwhile, 40,465 people have now died with the virus, an increase of 204, according to the latest government figures.
A further 10 people have died of coronavirus in Wales, while there were six deaths registered in Scotland and one in Northern Ireland.
Earlier, NHS Providers deputy chief executive Saffron Cordery said trusts were also nervous about the imminent lifting of some patient visiting restrictions.
She said they needed time to "put in place processes and guidance to ensure that patients can receive visitors safely and while adhering to social distancing and infection control measures".
Mr Hopson's criticism was echoed by the British Medical Association (BMA), which warned there was "little detail" on how the policy would be implemented, where the masks would come from or how outpatients and visitors would be given them.
Consultants committee chairman Dr Rob Harwood said: "Given the lack of PPE supplies throughout the Covid-19 pandemic, it is absolutely crucial that the government ensures there are enough supplies of face masks for staff, and adequate provision of face coverings for outpatients and the public by the 15 June."
It comes as the UK's death toll passed 40,000 on Friday according to government figures.
The UK is only the second country - after the US with 108,000 deaths - to pass the milestone.
Also at the Downing Street briefing, Mr Hancock appealed to people not to attend large demonstrations with more than six people, saying he was "appalled" by the killing of George Floyd in the US but "coronavirus remains a real threat".
Thousands ignored his plea to take part in the protests across the UK, with the majority of those at the London gathering wearing face coverings.
The World Health Organization (WHO) has changed its advice on face masks, saying they should be worn by the general public in situations where social distancing is difficult, eg on public transport, in shops - particularly for over 60s and those with underlying health conditions
In other developments:
- In north-west England many schools will delay reopening until 22 June over fears that the spread of the virus is increasing
- Some older people in care homes are being asked to pay more than £100 a week extra in fees to cover the costs of coronavirus
- The Duke of Cambridge has revealed he has been anonymously volunteering on a crisis helpline during lockdown
- The government should halve the two-metre social distancing rule if businesses in the hospitality industry are to survive when they finally reopen, trade organisations have warned
- In the first British classic horse race since sport returned, Kameko beat favourite Pinatubo to win the 2,000 Guineas at Newmarket.