Britain's Cabinet Office will investigate whether an international trade minister breached conduct rules by asking his secretary to buy sex toys as allegations of sexual harassment roil Parliament.

Health Secretary Jeremy Hunt says Mark Garnier will face an investigation after the minister's former secretary told The Mail on Sunday that Garnier gave her money to buy two vibrators at a Soho sex shop and called her a disparaging name in front of witnesses.

The story follows reports that female staffers and members of Parliament have created message groups to warn colleagues about harassment.

Hunt told ITV's Peston on Sunday program that people would be angry about the allegations because "this shows that in our own backyard we don't live up to the high standards that we would expect others to."