London, June 9 (RHC)-- Britain's anti-nuclear activists have blocked entrance to a nuclear bomb factory for more than three days, bringing the construction work at the firm to a halt.

Peace campaigners from the Trident Ploughshares group began a month-long action on Monday against the UK's Trident nuclear weapons program at AWE Burghfield in Berkshire, where warheads are assembled and maintained.

Protesters made a human blockade on roads around the factory.  A number of activists from other countries, such as Belgium, France and Germany, also joined the protest on Wednesday to show their solidarity.

Trident Ploughshares spokeswoman Angie Zelter said that this was the first time they'd sustained a blockade "from one day and overnight into the next for three full days and it is still continuing."  She emphasized: "We want an end to the threat of nuclear annihilation."

The protest came after reports that the factory had been working on a secret program to upgrade the existing Trident arsenal and to develop a new warhead.  According to a report by the Nuclear Information Service, AWE Burghfield is upgrading the current warhead to produce Mark 4A that will be more accurate with more destructive power.

Zelter also said between 20 to 30 activists are involved in the blockade at any one time, including an 87-year-old man and another activist who is in a wheelchair.

Activists say the upgrade of Trident arsenal is expensive and unsafe for contemporary warfare and in violation of Britain's international commitment.  Supporters of the Campaign for Nuclear Disarmament (CND) and a number of European anti-nuclear campaigns are expected to join the month-long move.