A mysterious underground tunnel measuring 23 feet long has been discovered near the venue for this summer’s Pan Am Games in Toronto, the CBC reported.

The tunnel – which measures around 8 feet high and 23 feet long – was dug in the woods near Toronto's Rexall Centre and York University's Keele campus, according to the CBC. The find, discovered by police several weeks ago, was made public Tuesday.

Authorities said at a press conference Tuesday that the tunnel posed no risk to the event, but they are seeking the public’s help to find out who built the tunnel and why.

The tunnel was large enough for a person to stand in and was equipped with lights powered by a generator. It was filled in by authorities, sources told the CBC, after pieces of evidence – including a rosary with a Remembrance Day poppy affixed to it – were recovered.

The tunnel reportedly was found by a Toronto and Region Conservation Authority employee who was walking near the organization’s headquarters in mid-January. He noticed a piece of corrugated steel in the woods and lifted it up to discover the tunnel.

Sources told the CBC that authorities essentially ruled out the possibility that the tunnel was going to be used as a drug lab or marijuana-growing operation.

"There’s no criminal offence for digging a hole," Deputy Chief Mark Saunders said.

Tennis Canada, which operates in the Rexall Centre, said it is working with police in the investigation. The Pan Am Games are scheduled for July 10-26.

"I would think that they would want to have some level of assurance that this was not targeting the Games or targeting any other facility around there," said Ray Boisvert, the former assistant director of intelligence at the Canadian Security Intelligence Service.

Investigators were in the area a few weeks ago and spoke with grounds crew while police combed the woods nearby, the CBC reports.

No suspects have been named in the case.

Click for more from the CBC.