Bomb squad officers in Madrid have carried out a controlled explosion after a practice hand grenade was thrown over the wall of a centre for unaccompanied foreign minors in the north-east of the Spanish capital.

A spokeswoman at the Madrid headquarters of the national police force said the grenade carried a small amount of explosive. There were no reported injuries.

“Staff at the centre found a suspicious object in the centre’s patio between 8.30 and 9 this morning,” she said.

“Specialist officers from the national police force attended and evacuated the children to a safe area. Bomb squad officers detonated the object, which was determined to be a practice grenade with little charge, which had been thrown into the centre’s grounds in a bag from outside.”

The reception centre, in the Hortaleza neighbourhood, recently made headlines after it was singled out by Santiago Abascal, the leader of the far-right Vox party.

Abascal, who lives in Hortaleza, said the centre and its residents – many of whom are from north and sub-Saharan Africa – had left many local people feeling unsafe.

“I live in a working-class Madrid neighbourhood – Hortaleza,” he said during an election debate last month. “And every time I’m on the street – and there’s a centre for unaccompanied foreign minors there – I run into women who come and tell me that the police tell them not to wear their jewellery on the street; and mothers who are worried that their daughters are coming home late and are scared of being assaulted.”

Unaccompanied foreign minors – known by the Spanish acronym menas –were also targeted by Rocío Monasterio, Vox’s leader in Madrid, who called them “a serious problem in our neighbourhoods”.

Wednesday’s attack was not the first time that children at the centre have been targeted. In the fortnight before the election, on 10 November, some of them were beaten with oars and clubs.

Adriana Lastra, the vice-secretary general of the ruling Socialist party, said that words had consequences. “This is what hate speech brings,” she wrote on Twitter. “It needs to be fought online, on the streets and in our institutions.”

Vox also condemned the attack. But in a statement, it accused its opponents of trying to make political capital out of Wednesday’s events. “It’s disgraceful that violence – which is never justified – should be used for political ends,” it said. “We await the conclusions of the investigation by state security forces.”