More than 450 attacks, most of them rape, were carried out on boys and girls aged three to 14

Two men who groomed and abused hundreds of children at a campsite in Germany over a period of more than 20 years have been jailed by a judge who said she was “lost for words” at the severity of their crimes.

Victims’ families said they hoped the attackers would spend years behind bars. The nation’s judiciary, police, youth services and politicians came under fire during the 10-week trial for their slowness to act, despite suspicions about the men expressed by children and their parents years before.

Herbert Reul, the interior minister for the state of North Rhine-Westphalia where the abuse took place, has conceded that authorities have “not been on the ball – but half-asleep” on tackling child abuse, and promised to ensure the issue was put at the top of the political agenda.

Andreas V, 56, and Mario S, 33, whose full names were not released in accordance with German law, will spend 13 and 12 years in prison respectively, followed by a period in preventive detention, a punishment reserved for the most serious of criminals because of the risk they pose to the public’s safety.

The men were accused of more than 450 incidents of abuse, most commonly rape, of 32 boys and girls, between 1998 and 2018. Their victims were aged between three and 14. Some of the children were holidaying at the camp in Lügde, close to Hamelin in northern Germany; others were visiting a girl who was being fostered by Andreas V, who was also raped by him and was in turn used to lure other children to his caravan.

Some of the children were promised laptops and other gifts, such as horse-riding sessions, if they complied. The men filmed their attacks, and thousands of hours of footage seized by police formed a central part of the evidence against them. Despite social service visits of up to four hours a week to Andreas V, who was registered at the camp as a permanent camper, social workers failed to report anything suspicious.

Investigators have said they believe that more than 1,000 children may have been victims of the men, but that because of the typical comings and goings of the campsite it had been almost impossible to contact many families. While some had approached the police, many may never come forward, they said.

Thirty-three witnesses, including 16 victims and 12 relatives, gave evidence at the trial in Detmold, much of which took place behind closed doors to protect identities.

The judge, Anke Grudda, said she could not put the horror of the crimes into words. “Words like vile, monstrous, despicable, are insufficient to describe these deeds,” she said. “Even after 10 days of hearing the evidence, I am completely bewildered.” Addressing the guilty men, she said: “You have degraded 32 children and youngsters into the objects of your sexual covetousness and destroyed 32 childhoods.” She said she did not believe the men understood the severity of their crimes.

National outrage over the case, which came to light in January, has been fuelled by a catalogue of failings by authorities. Johannes-Wilhelm Rörig, who was appointed as the federal government’s independent ombudsman for child sexual abuse in 2011, said the Lügde case had thrown a spotlight on the “shocking obliviousness and inappropriate lack of concern about the dangers of sexual violence”, which he said were widespread.

Rörig has made public his concerns that the subject is not taken seriously, not least because he has frequently had to push the government to decide on whether it was going to extend his role, and due to a lack of resources and personnel.

He has called for greater cooperation between youth welfare offices, police, judiciary, child-care workers, schools and the health system.

Spiegel magazine recently highlighted the lack of investigators in Germany dedicated to dealing with child abuse, which became an issue of widespread national debate in 2010 after a series of scandals in both Catholic and Protestant boarding schools. In North Rhine-Westphalia, the country’s most populous state, out of a 40,000-strong police force there are just 104 positions dedicated to tackling child abuse.

Last year, there were 2,500 investigations into child abuse in the state. In June, the police had 557 outstanding warrants to search properties in connection with child abuse images cases that had not been carried out due to a lack of personnel, Spiegel reported, allowing suspects the opportunity to destroy evidence.

• This article was amended on 7 September 2019. North Rhine-Westphalia is Germany’s most populous state, not its largest as an earlier version said.