German police have arrested a teenage asylum seeker suspected of planning a suicide attack in Berlin.
The suspect, 17, was arrested in the Uckermark, a district in Brandenburg, the state's Interior Minister, Karl-Heinz Schröter, announced.
He entered Germany in 2015, police said. They have not confirmed reports that he is Syrian.
In December, a jihadist killed 12 people with a lorry at a Berlin Christmas market.
That attack by Anis Amri, a Tunisian, put security services under intense scrutiny because of the way in which the attacker, who was later shot dead by police in Italy, evaded their surveillance and crossed European borders undetected.
Special forces arrested the teenager after police received a tip-off, Brandenburg police tweeted (in German). He had sent a message to his family saying farewell and that he was joining the "jihad", the police said.
The boy told his family he planned to carry out a suicide attack, Mr Schröter said.
His ministry said the suspect was Syrian but police tweeted that neither the "Syrian nationality" nor "concrete attack plans" could yet be confirmed, and that investigations continued.
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The suspect had been living in a home for unaccompanied underage refugees in Uckermark since 2016 and had never before come to the attention of police.
He is currently being questioned and the home is being searched by the state criminal investigation office, Brandenburg police said.
Details of the plot cannot be released due to police operations, which are ongoing, the police added.
Some 280,000 asylum seekers arrived in Germany last year, a drop of more than 600,000 compared to 2015.
Chancellor Angela Merkel's decision to temporarily open the country's borders at the height of the European migrant crisis divided opinion and immigration is an important political issue ahead of the parliamentary election later this year.
Mrs Merkel recently moved to try and ramp up deportations of failed asylum seekers.
Tunisia had refused to take back Anis Amri after his asylum bid was rejected and pressure has increased on Mrs Merkel's government since the December attack.