WASHINGTON, Aug 17: US authorities may ask Pakistan to tighten security at ports after unlisted items in two containers shipped from the country caused a security alert at Seattle port.

The panic began when US customs agents peered through the containers using a gamma-ray device, and detected items that did not match the manifest.

Authorities got more panicky when a bomb-sniffing dog indicated that the containers might contain explosives.

Police were called who evacuated workers and set up a half-mile perimeter around the port.

Later, a bomb squad was called which searched the containers and found no explosives.

Officials said the containers were supposed to contain oily rags, which are often shipped internationally for recycling or use in packaging. But they also contained other items.

The ship had originated in Hong Kong and made stops in China and Pakistan before arriving in Seattle on Monday.

Officials at the Seattle port complained that containers from Pakistan often had unlisted items and said they planned to ask federal authorities to advise Islamabad to further tighten security at their ports.

Meanwhile, security officials said that the woman who on Wednesday caused a London-Washington flight’s diversion to Boston had begun her journey in Pakistan.

Catherine C. Mayo, an American citizen, was returning home after vacationing in Pakistan, the officials said. During the flight, she got panicky and had an altercation with the crew.