As first reported in our sister newspaper, the Driffield Times on Wednesday, the boys, aged 11 and 12, were detained in connection with the incident, which happened on Monday evening.

The boys have now been released on bail and told to report back to officers on a date in November.

Meanwhile, detectives have appealed for witnesses to the blaze, which completely gutted an office at the new multi-million pound facility, to come forward.

Detective Chief Inspector Nigel Sawyer, who is leading the inquiry, said he wanted to hear from anyone who was in the area at around 6pm on Monday and who saw anyone acting suspiciously.

He said: "It is still a live investigation. It was a substantial fire and one that we are taking extremely seriously.

"Did you see anyone hanging around? Did you see anyone going into the sports centre?"

Anyone with information about the incident is asked to contact the police on 0845 6060222.