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Police are investigating the release of bedbugs in a US Walmart after staff found two containers of the insects hidden inside the store.

A manager at the supermarket in Pennsylvania found the bedbugs last week in a pill bottle inside a coat for sale.

Investigators believe the blood-sucking parasites were left at the shop in Edinboro deliberately.

Walmart says there is no evidence of an infestation at the store.

No suspects have been identified so far in the investigation, state trooper Cindy Schick told the BBC.

Police have not yet established a motive for the release of the insects at the Walmart, about 90 miles (145km) north-east of Cleveland.

The bedbugs were discovered by a Walmart manager on 2 January in a sealed pill bottle hidden inside a boy's jacket in the store's clothing department.

Media playback is unsupported on your device Media caption The BBC's Victoria Gill was shown how bedbugs feed

A health safety company was called to the store and confirmed the insects were bedbugs. The pest controller then found more bedbugs crawling around a men's fitting room.

On Saturday, two days after the bugs were first discovered, a second closed pill bottle containing dead bugs was found in the men's clothing department.

A spokeswoman for the retail giant told the BBC that Walmart was co-operating with the police investigation.

Image copyright Justin Sullivan/Getty Images Image caption The Pennsylvania Walmart has blocked off the impacted area

"Our third-party pest management service has visited the store, and after conducting a thorough review found no evidence of an infestation," spokeswoman Tara Aston said. "We believe this to be an isolated incident and are taking all the necessary steps to help ensure a safe environment for customers and associates."

Walmart said it had contacted other stores in the area and confirmed theirs was an isolated incident.

Bedbugs are present all over the world, but in recent years Europe, the US, Canada and Australia have witnessed a resurgence of the pests.

Image caption The red welts left by bedbugs can be extremely itchy

There are 100 different species of bedbugs and most of them live on bats. Only two feed on humans.

The insects feast on the blood of their sleeping victims, inflicting itchy, red welts.

They are a difficult pest to eradicate. Bedbugs can live for up to a year without a blood meal and new studies indicate that bedbugs in the US have developed a resistance to popular insecticides.

Though bedbug bites are not considered dangerous, an allergic reaction to multiple bites can require medical attention.