The victim, a man in his 60s, died in hospital on Sunday afternoon after he picked up an object at the Vårby Gård station southwest of the city centre, and it exploded. A 45-year-old woman was also injured in the blast.

Police had earlier said they suspected that the object had been a hand grenade, and on Tuesday afternoon a spokesperson confirmed that this was the case.

“Our technicians on the scene have now been able to confirm that it was a hand grenade,” police spokesperson Lars Byström told the TT news agency. He said police did not yet know how the grenade exploded, adding that anyone with information should come forward to them.

Police earlier said that the man who died was unlikely to have been purposely targeted by whoever left the explosive at the station.

Vårby gård is one of 61 areas across Sweden considered to be 'vulnerable', and defined as “a geographically defined area characterized by a low socio-economic status where criminals have an impact on the local community”.

READ ALSO: What you need to know about Sweden's vulnerable areas 

A map showing the location of the subway station, in a southwestern suburb of the capital.

Sweden’s Justice Minister Morgan Johansson has called for an amnesty of the weapons and tougher laws in order to get hand grenades off Sweden’s streets.

Speaking at a government press conference on Tuesday, Johansson said: “It won’t be an amnesty that ultimately breaks down this type of crime, but it prevents such accidents in the future.”

Sunday’s incident has put the spotlight on hand grenade crime, which appears to be on the increase in Sweden over the last few years. Figures provided by the Dagens Nyheter daily last year showed that there were 27 instances of grenades exploding in Sweden during 2016, compared to 10 in 2015.

Johansson said that a harsher weapons law which came into force at the start of this year should help to reduce this kind of criminality. Among the measures introduced was a change in the minimum punishment for aggravated weapons crime and aggravated crime against compulsory licensing for explosives, which was increased from one to two years' imprisonment.

READ ALSO: Sweden's new laws to watch out for in 2018

The minister had already raised the possibility of a hand grenade amnesty — which would be the country's first — in October last year. At the time, he said the proposal for an amnesty between October 2018 and January 2019 would be brought to the parliament in February this year.

While he said that the most effective crime-fighting measures was to deal with the perpetrators themselves, Johansson said on Tuesday: “It can also be a good idea to take in these hand grenades or other explosive goods to get them away from society. The more that are out there, the greater the risk that they go off.”

READ ALSO: Why Sweden has more fatal shootings per capita than Norway or Germany