A troop of people dressed up as monkeys joined Lib Dem environment spokesman Norman Baker yesterday in calling for a total ban on primate testing in the UK.
The monkeys, wearing bowler hats and carrying briefcases, were not allowed into Downing Street for security reasons, so it was left to the MP for Lewes to present the 163,000 signature petition to the prime minister.
Government figures show more than 3,000 non-human primates were used in experiments in 2003, an increase of 20 per cent on the previous year, making the UK one of the largest users in Europe.
Yesterday's petition launched the start of the Next of Kin campaign, which is supported by campaign group the British Union for the Abolition of Vivisection (BUAV) and hopes to ban primate testing across the whole of the EU.
"I wholeheartedly support the BUAV's campaign to ban testing on primates and wish them every success," Mr Baker said.
"I am appalled at the use of these intelligent and sociable animals who share so many qualities with us. One can only imagine the suffering they endure."
Next of Kin intends to highlight the ethical concerns over the testing of primates, which are intelligent and live in complex social systems that are seriously disrupted by laboratory work.
The campaign also raises questions about the efficiency of primate research for diseases such as Alzheimer's and Parkinson's, saying the procedures "inflict much suffering and yet have very little scientific value".
Comedian Alexei Sayle is one of those supporting the BUAV campaign, saying: "These sociable creatures share with us the ability to, not only remember past events, but to anticipate the future.
"One can only imagine, therefore, the suffering these intelligent creatures endure when their only experience of life is of confinement in a barren cage, followed by an experimental procedure, followed by being left - sometimes completely alone - to ponder on their next ordeal."