Counter-terrorism police investigating a fire at a DHL depot have arrested a Romanian man on suspicion of assisting a foreign intelligence service.

The blaze at a warehouse in Birmingham in July came amid fears of a growing number of Kremlin-sponsored sabotage plots.

The Metropolitan Police said the 38-year-old was arrested on suspicion of assisting a foreign intelligence service under the National Security Act after he flew in to the UK on March 19.

He was arrested at Stansted airport, taken to a London police station and released on bail to a date in July.

It was reported that counter-terrorism police were investigating whether Russian spies planted a bomb in a parcel that caught fire.

A CTP spokesman said: "Due to the circumstances, and the specialist capability and expertise in investigating such matters, the investigation is being led by officers from the Met's Counter Terrorism Command with support from colleagues from Counter Terrorism Policing West Midlands.

"The investigation remains ongoing and one man has been arrested for offences under the National Security Act.

"The 38-year-old Romanian national was arrested on 19 March after arriving at Stansted airport on an inbound flight to the UK.

"He was arrested on suspicion of assisting a foreign intelligence service, under section 3 of the National Security Act 2023 and he was detained under the Police and Criminal Evidence Act (Pace)."

MI5 Director General Ken McCallum has warned Moscow and Iran are creating more chaos through arson, murder, kidnap and sabotage conspiracies.

And the threat Russia poses on Britain’s streets is “getting worse”, he warned.

Mr McCallum said Russia’s GRU intelligence agency, which was responsible for the Novichok poisonings in Salisbury in 2018, is behind the "sustained mission", adding that Putin’s “henchmen” are ramping up arson and sabotage operations across Europe “in the misguided hope of weakening Western resolve”.

Nobody was injured in the fire, in July, before it was put out.

But a similar incident in Leipzig, Germany, has sparked fears it is part of a wider Russian campaign to carry out arson and sabotage plots in Europe.

This is primarily to weaken military support for Ukraine and divide the West, it is understood.

At least 24 alleged saboteurs have been arrested so far this year after being recruited by Russian spy chiefs.

A wave of fires at arms factories and military-related industrial sites in the West has alarmed intelligence chiefs. Suspected plots have been detected in London, Germany, Czech Republic and Sweden.