He warned that the last blockades threatened the economy and "real risks will remain" to the country if protesters calling for fuel tax cuts behaved in an "extreme and irresponsible way".

If the protests had persisted much longer they would have caused severe damage to many firms

Jack Straw

Mr Straw told the House of Commons future blockades would only hurt the weak and vulnerable.

His statement came after energy giant Shell was attacked for posting record profits on the back of the soaring world oil price.

It announced an 80% jump in earnings for the last three months, to �2.24bn.

Jobs threatened

Shadow Home Secretary Anne Widdecombe said the fuel crisis had been caused by the government's refusal to listen to calls from the Tories and the general public to cut fuel tax.

Mr Straw said the Fuel Task Force had consulted a range of people affected by the blockades to draw up the defence strategy.

He said the threat to the economy was clear from reports by the British Chamber of Commerce drawn up since September.

Police are prepared to deal with demonstrations

He said 25% of businesses in St Helen's, for example, lost orders and 6% were forced to lay off staff temporarily.

In Peterborough, 40% of firms lost sales and 16% laid off staff.

"If the protests had persisted much longer they would have caused severe damage to many firms, some of which would have never recovered," he said.

He said the protesters were selective about who was allowed to receive fuel, such as doctors, but the blockades did disrupt essential public services.

Intimidation

Mr Straw said: "We hope to protect food depots, keep roads open and protect other targets other than fuel depots."

He said soldiers could be drafted in to drive tankers "as a last resort" but he gave no details of what the other targets might be, nor any detail of the measures being taken.

The home secretary said most of the protesters were peaceful but he published a list of 180 documented cases of intimidation of tanker drivers.

"The right to argue, to complain, and to protest is an essential feature of our democratic society," he said.

"Preventing law abiding people from going about their business and threatening the well-being of the country is not."

The incidents range from verbal abuse and threats, to objects thrown from bridges and physical intimidation.

Examples of entries include:

• 8 September - Driver on a bike followed home by a car full of protesters threatening that they knew where he lived.
• 12 September - Protesters took a photograph of a tanker driver and told him it would appear on the internet.
• 13 September - A brick was thrown through a cab window, showering the driver with glass.

Campaigners say stories of intimidation have been exaggerated.

They are calling for a 26.2p per litre cut in fuel duty and have threatened to blockade London with up to 25,000 lorries should their demands be ignored.

Limitations

But Mr Straw said government action was restricted by the need to keep interest rates low, supporting pensioners and continuing investment in the public sector such as schools, transport and police.

He warned those thinking of staging future blockades as the protesters' 60 day deadline expires in 11 days' time.

"The consequences of such disruption are obvious - and they would hit the weakest and most vulnerable first," he said.

"Those now seeking further disruption must understand that the demands they have made could not be met without great damage to jobs and industry, to essential services including the NHS, to pensioners and children."

Tory leader William Hague was also expected to appeal to protesters not to make families suffer.

"Protests that involve direct action, that are not peaceful, that are not legal or that cause suffering to hard-working families will rightly lose the support of the public," Mr Hague is expected to tell North East business leaders in Newcastle on Thursday.