A United Airlines passenger plane travelling from London to Washington has been diverted to Boston because of a security alert. Officials say a female passenger had a confrontation with the crew. There has been no official confirmation of earlier media reports that the passenger had banned items including a screwdriver and matches. Some reports say the woman had an anxiety attack. Authorities say the captain declared a security emergency and the plane, carrying about 180 passengers, was escorted to Boston by airforce jets. Security personnel checked all of the plane’s luggage on the tarmac.