A man has been jailed for a year in New York for calling in a series of hoax bomb threats, many of which targeted institutions in the UK.

David Hart was prosecuted by US authorities after a joint investigation by Scotland Yard and the US department for homeland security.

In recordings of some of the calls, released by the Met police, Hart can be heard asking a call handler what they would do if he had “put a bomb in Guy’s Thomas hospital”.

The call was an apparent reference to two separate sites in London that are managed together by Guy’s and St Thomas’ NHS foundation trust.

He could also be heard telling a switchboard operator at a major London hospital: “All right, I put a bomb in you guys’ corridor bathroom … You have exactly about 12 seconds to get out of that building.”

Scotland Yard said the 22-year-old appeared at the US district court for the northern district of New York on 6 January.

The court heard that from late October to mid-November 2023, Hart made 95 calls to numbers in the UK, 66 of which were made to numbers in London. While not all calls connected successfully, many did.

“The venues targeted included seven hospitals, six bars, restaurants and supermarkets, two police force control rooms and a cancer information and support services centre. Hart twice attempted to call Westminster Abbey but he did so when it was night-time in the UK, meaning the calls were not answered,” the Met police said.

“In those calls, he typically told the person who answered the phone that he had planted a bomb at their location, which would soon explode. He would make multiple calls, sometimes days apart, to the same victims. The calls were sustained and persistent, sometimes lasting almost half an hour.

“On other occasions, he claimed to have planted a bomb in a hotel basement, describing it as homemade and filled with nails.”

Although police said some of the call recipients were sceptical the threats were genuine, they still felt they had to take precautions. Security staff at some of the threatened locations searched their venues and one of the hospitals went into full lockdown while they searched for explosive devices.

The court was satisfied Hart knew the calls would be received as the threats he intended them to be, police said.