Opponents of hunting are calling for urgent amendments to the Hunting Act which they say still allows foxes to be "terrorised and killed".

The call came as hunts across the West were out in force at the weekend celebrating the opening of the fourth season since the hunting ban came into force.

Since February, 2005 it has been illegal to hunt wild mammals with dogs, with certain exemptions.

Hunts are still able to exercise hounds, and to "trail hunt" – using a scent laid for hounds to follow.

Some hunts use a bird of prey exemption, allowing hounds to flush quarry out to the bird.

Some foxes are still being killed by hounds but hunts maintain that kills are accidental and happen while they are acting within the law.

No hunts have been disbanded and many are reporting increased membership.

Anti-hunt monitors maintain that film footage from across the country shows that is not always the case.

Yesterday, campaign group Powa – Protect Our Wild Animals – urged MPs and the Government "to remember all of the cruel and barbaric practices that the Hunting Act was meant to outlaw".

At the moment the prosecution must satisfy the court that a defendant intended to hunt.

Powa wants the law amended so individuals can be prosecuted for acting recklessly.

Penny Little, spokeswoman for Powa said: "It was an historic achievement when the Hunting Act reached the statute books. But it is vital that we remember the terror and torment suffered by wild animals hounded for so-called 'sport' and remember the aim of this legislation was to deter or punish this cruelty which continues despite the ban."

Helen Weeks, a hunt monitor from Somerset, said: "Anyone who comes out with us will see that the only thing standing between the hunted animal and the hounds are the monitors and their camcorders.

"They will see hunt supporters using intimidation and violence to stop us from filming and they will see how many hunts are left to their own devices leaving our wildlife in great peril."

Veteran hunt monitor Kevin Hill said: "Most hunts I monitor go out with the intention of hunting. Last season I didn't see one trail-laying. Hunts are going to the traditional places where they will find foxes and put hounds into dense cover where it would be impossible to lay a trail.

"I don't know of one hunt which has retrained its hounds to follow a scent trail rather than an animal, and I have seen foxes chased and killed.

"Generally police forces across the country are not doing enough to uphold the law.

"They investigate when we give them evidence and put it to the Crown Prosecution Service but the CPS comes back with various reasons why the hunt won't be prosecuted."

Delly Everard, Countryside Alliance spokeswoman for the West, said: "Hunts act within the law and trail hunting takes place but accidents happen. It is now the fourth full season since the Hunting Act came into force and hunting is more popular than ever.

"I think that is probably a measure of the real community determination to keep the infrastructure of hunting together until the Act is repealed, and we believe it will be because it's a prejudiced law that isn't working. It does nothing for animal welfare.

"For example, you are allowed to use a terrier to protect pheasants, but not lambs. We would like to see an appropriate law based on wildlife management and scientific findings not one introduced because of personal prejudices."

Hunts are pinning their hopes for a repeal of the Act on a Tory win at the next General Election. The Tory manifesto at the last General Election promised Government time for a vote to repeal the Act.

Countryside Alliance chief executive Simon Hart has said: "Hunting has all the ingredients of an epic tale with its origins in liberty and tolerance and as we all know it now needs is a happy ending.

"If we continue to be as resolute, continue to make our case and continue to work for repeal that ending is in sight."