Hong Kong (CNN) Four British citizens have been arrested by Chinese authorities in eastern Jiangsu province, the UK Foreign Office said Friday, two days Chinese police announced a drug raid there involving 16 foreigners.

In a statement Wednesday, Chinese police said they had arrested 19 people in Jiangsu, including 16 foreign citizens after they tested positive for illegal drugs.

Those arrested included seven teachers and nine foreign students, according to police in the city of Xuzhou. Police did not provide details relating to the specific nationalities of those arrested or the type of narcotic used.

In a statement on their social media, English language training provider, Education First (EF), said with "deep regret" that some of their teachers had been involved in the drug use.

CNN has reached out to EF for comment. The UK Foreign Office could not confirm whether the two cases were related, nor when the Britons were arrested.

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