Chisinau  - A suspected hand grenade exploded in a crowded Moldovan city square injuring 40, the Infotag news agency reported Thursday.

The blast took place late Wednesday evening at the Arch of Triumph monument in the centre of the Moldovan capital Chisinau.

Metal fragments from the explosion left 37 victims hospitalised, Internal Affairs Minister Viktor Katan said.

Most of the victims were Chisinau youth, the majority receiving injuries to their legs or arms, according to the report.

Tens of thousands of people were on Chisinau's streets on Wednesday evening celebrating the local Day of the City holiday.

A street rock concert was in progress in Triumphal Arch square at 10:30 pm (1930 GMT), the time of the explosion.

Pop groups from Russia, Romania and Moldova reportedly continued with playing for another 30 minutes, until police ordered the concert stopped.

A police investigation of the blast site uncovered "extremely strong evidence" that a Soviet-era RG-42 hand grenade caused the explosion, Katan said.

"We have yet to determine if it (the explosion) was the result of criminal intent, or an accident," he said.

A civil war between Moldova's majority Romanian-speakers and minority Russian-speakers ended in 1992 with the de facto secession of the Transnistria province.

Tensions between Moldova and Transnistria remain high, but war-related violence is uncommon along a ceasefire line between the two sides' militaries, and rare in towns and cities. (dpa)