Police stand guard outside the Stockholm District Court in Stockholm, Sweden, April 11, 2017.(Xinhua/Rob Schoenbaum)

STOCKHOLM, April 11 (Xinhua) -- The key suspect in Friday's truck attack in Stockholm, 39-year-old Rakhmat Akilov, has admitted to committing a terrorist crime, his lawyer told a Swedish court on Tuesday morning.

The Stockholm District Court ruled that Akilov should be detained pending trial for committing a terror offence.

Akilov, an Uzbek citizen, was arrested in northern Stockholm on Friday, five hours after the terror attack in a busy shopping street of the city.

It is unclear when Akilov arrived in Sweden but he has apparently lived in the country under different identities and applied for asylum in 2014. His application was rejected last year.

In February, the Swedish Migration Agency handed over Akilov's case to the police since he had absconded. He has been wanted by the authorities since February.

The evidence against a second person arrested on suspicion of involvement in Friday's attacked turned out on Tuesday not to be strong enough for keeping him in detention. However, he will not be set free since he had previously received a deportation order.

A truck rammed into people on a central Stockholm street on Friday before crashing into a department store, killing four people and injuring 15 others. Nine of the wounded are still in hospital, two are in critical condition.