Police were forced to apologise after wrongly seizing legal highs not covered by new drug laws.

Officers from Sussex Police initially appeared to give themselves a pat on the back after seizing dozens of "poppers", and posted a picture of the haul on the Crawley Police Twitter account.

The caption read: "First Day, first seizure in Crawley by PC Goater! One and only one warning given. #NoSecondChance #PoppersIncluded."

But hours later police were forced to return the poppers - a chemical designed to give the user a short high - after Twitter users pointed out their error.

Joshua Dixon (@JoshDixonTweets) replied: "Hi PC Goater @Crawley_Police are you sure you're meant to be confiscating poppers? x."

Despite initially denying they were in the wrong, police eventually admitted their error and said they had returned the goods.

They told their followers: "Crawley Police can announce that the 'poppers' were seized in error in good faith. All goods will be returned to the shops with apologies."

On Thursday new legislation banning the sale of legal highs that mimic the effects of Class A drugs was introduced, with anyone caught facing up to seven years in prison.

Poppers were initially included as part of the new legislation, but were later exempted after advisers said the drug did not fall within the scope of the current definition of a "psychoactive" substance in the legislation.

In January the Conservative former minister Crispin Blunt said he used poppers and called on them to be removed from the ban, calling their inclusion "fantastically stupid".

He said: "I use poppers, I out myself as a popper user, and would be directly affected by this legislation and I'm astonished to find that it's proposing to be banned and, frankly, so were many other gay men."