The devices, each containing about 20 grams (half an ounce) of dynamite, were found during a routine police check on Monday outside a British-owned Littlewoods store near the Piskaryovskoye cemetery.
Prince Charles laid a wreath at the cemetery the following day on his four-day visit to St Petersburg which ended yesterday.
It is thought there was no direct link between the bombs and the Prince's visit. Home-made bombs have been used by local mobsters to intimidate or to extort money. 'The bombs were rather small,' a police spokesman said. 'It was probably just an act of hooliganism.'
St Petersburg has seen a number of minor bombings in the past two years as rival criminal gangs sought to extort money from private shops or destroy business competitors.
But there was no obvious anti-British feeling in the city and Prince Charles, the first member of the royal family to visit St Petersburg since the 1917 revolution, has had a warm welcome on the streets.
The shop is one of three owned by Littlewoods in the city, and the Prince visited one of the other branches during his visit. Neither Buckingham Palace nor Ian Williams, manager of the store, made any comment.
Prince Charles has been the centre of a number of security scares recently. In Australia in January a man with a starting pistol got to within a few feet of him. The following month saw a similar incident in New Zealand involving a man wielding an aerosol can.
Later that month thieves broke into the Prince's apartment in St James's Palace, and stole personal items. In March a man with a knife was seized in a crowd waiting for Prince Charles to arrive at a London film premiere.Reuse content