Police at the G7 summit in south west England evacuated a hotel in Falmouth after reports of a suspicious package early on Thursday morning, which they later called a "hoax incident".
US President Joe Biden arrived in Britain on Wednesday evening and is staying in the English seaside resort of Carbis Bay, about 25 miles away from Falmouth, where most media covering the event are staying.
Security for the G7 event, the first in-person meeting of the leaders of major developed economies for nearly two years, is tight.
"We currently believe that this was a hoax incident and a criminal investigation has been launched," Devon and Cornwall Police said.
Police have closed off roads and coastal paths to Carbis Bay, the small seaside resort which is hosting the event, erecting steel fences and putting other restrictions in place.