Construction group Montpellier has called in the police after shareholders received threatening letters from animal activists.
Shares in the group, which reported a £20.7m loss a fortnight ago, fell 19% on Monday when shareholders opened letters ostensibly from Montpellier chairman Roy Harrison. The letters warned of "prompt activity from the animal rights movement" if investors did not sell their shares.

The activists aim to undermine work at Oxford University's £18m animal testing laboratory, which is being built by Montpellier subsidiary Walter Lilly & Co.

A company spokesperson said: "These letters purport to be from certain members of the senior management team at Montpellier. This is false."

The activists, who have not been identified, warned that investors had a month to sell their shares, or their details would be published on the internet.