• Specialist unit is looking into complaints involving more than 300 clubs • About 23% of those complaints relate to the sport at professional level

The specialist police unit investigating child abuse in football has received more than 400 new referrals since publishing its last updated figures and is now investigating complaints involving more than 300 clubs.

According to information passed to the Guardian, about 23% of those complaints – with 311 clubs named – relate to the sport at professional level, with the vast majority of incidents referring to the 1970s, 80s and 90s.

By 31 March Operation Hydrant had received 1,432 referrals since Andy Woodward’s interview in November instigated what the Football Association chairman, Greg Clarke, has described as the worst crisis he can remember in the sport.

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The previous data, released in mid-January, put the number at 1,016 but a Freedom of Information request submitted by one of the survivors demonstrates that the figures have continued to rise steadily over the following three months.

The new information also shows that almost a third of the allegations relate to football in the north-west, with the National Police Chiefs’ Council receiving 457 referrals affecting that region.

In January the NPCC reported that 526 potential victims, who were aged between four to 20 when the abuse took place, had come forward, with allegations made against 184 individuals. Those figures have not been updated but the NPCC plans to release new data later this month and, despite the alleged abuse often being described as historical, it has also transpired in the past few weeks that the January figures included 46 reports of alleged incidents from 2005 to 2016.

The same statistics had 187 reported allegations from 1996 onwards and 23 relating to 2011 or later, raising questions about why the FA’s independent inquiry had a cut-off point “up until around 2005”. The inquiry began at the start of December and is expected to last around a year to 18 months.