Meghan Markle. Picture: Bang Showbiz

Kensington Palace has decided to increase security measures after a racist letter laced with a white powder was sent to Prince Harry and his fiancee Meghan Markle, who are poised to tie the knot at St George's Chapel at Windsor Castle on May 19.

A source explained: "The staff tasked with opening letters are now on high alert. They have been given goggles and protective face masks as anthrax and other substances can kill if they are inhaled.

"Staff have joked that it's like something out of that film, 'Outbreak', where they deal with the deadly virus. Police officials have also given them gloves usually worn to handle asbestos."

The new security measures are also designed to help reveal the identity of criminals.

The insider told the Daily Star newspaper: "The gloves will not only protect skin, but maximise the chance of the suspect's fingerprints staying on the dodgy mail."

The letter sent to Meghan, 36, on February 12 is still being investigated by detectives, with Scotland Yard treating the package as a race hate attack.

Meanwhile, it was recently reported that Prince Harry has invited his ex-girlfriends to his wedding.

The 33-year-old royal has apparently asked his two former long-term loves, Chelsy Davy and Cressida Bonas, to attend the much-anticipated ceremony.

A source recently said: "Harry has stayed good friends with Chelsy and Cressida, so they will be there. He made sure there were no hard feelings when they split up. I don't think Meghan will mind."

The British royal - who announced his engagement to Meghan in November - dated Chelsy, 32, for seven years, while his relationship with Cressida, 29, ended after two years.

Bang Showbiz