The Bill, scheduled to be introduced in next week's Queen's Speech, will also set out to protect wildlife and to safeguard nearly 40 of the country's most beautiful landscapes.
In a separate development, Jack Straw, the Home Secretary, is expected to announce on Tuesday that the Government will not legislate to ban fox hunting in the next session. But he has told anti-hunt MPs that they will get enough time to ensure passage of a private member's Bill.
The planned Countryside Bill, the first green legislation introduced by Tony Blair's government, would be a triumph for Michael Meacher, the Environment Minister, and John Prescott, the Deputy Prime Minister.
While its inclusion is not yet certain - the contents of the Queen's Speech have yet to be finalised - it has advanced up the Government's list of priorities.
Until recently, it was being kept out of the programme for the coming session, but the crisis in the countryside, criticism of the Government's failure to bring in green legislation and the abolition of hereditary peers - who were expected to mount stiff opposition - have ensured it a place in the provisional list.
Most controversially, the Bill, which will not be published before Christmas, would give the public free access to mountain, moorland, downland, heathland and common land in England and Wales. Ministers may also include powers enabling them to open other areas - such as the foreshore, riverbanks, lakesides and woodlands - without new legislation.
The Countryside Agency is to draw up maps of areas to be opened, and an "access forum" in each area will try to reach a consensus on how the right to roam is to be implemented. Landowners will be able to restrict access for limited periods for activities such as shooting or heather burning.
But ministers are having difficulty working out the details of a "sweetener" for landowners - the right to change the routes of public footpaths on their land.
Other measures will revolutionise protection for the 5,000 Sites of Special Scientific Interest (SSSIs). The main safeguard now is to pay landowners who threaten to damage or destroy them to desist.
English Nature, the official wildlife watchdog, reported last month that over a quarter of England's SSSIs were suffering continuing damage and neglect under this regime.
The planned Bill would allow the authorities to prohibit damaging activities. Landowners would be able to appeal decisions, but would have no right to compensation, and would be subject to an unlimited fine if they disobeyed the order.
The authorities will also get powers to force landowners to restore damaged SSSIs, to order to manage them better, and to purchase sites compulsorily as a last resort.
The landscape measures - exclusively forecast in The Independent on Sunday last March - will give far-reaching protection to England's 37 Areas of Outstanding Natural Beauty, including the Cotswolds, the Chilterns, and the Malvern Hills.
Originally established by the Attlee government - and recognised to be as beautiful as, if less wild than, National Parks - they have, so far, had little protection.
The Government has also promised to set up two new national parks - the New Forest and the South Downs.Reuse content