A marauding bear and a foul-smelling swimming venue have sparked alerts for Olympics organisers as the sporting action finally began in Japan. 

Sightings of an animal intruder caused alarm for police outside the Fukushima softball venue, which was hosting the first event of the Covid-delayed Games. Officers confirmed they had been unable to immediately track down the animal, which had been identified locally as an Asian black bear. 

Meanwhile, in Tokyo Bay, concerns have been raised about the water quality in the area where open water swimmers and triathletes are due to compete. A stomach-churning odour will greet competitors at the swimming venue for triathletes and open water swimmers, raising concerns about elevated levels of E-coli bacteria. 

Local reports said residents had complained that the bay smelled "like a toilet" immediately around the Odaiba Marine Park, an urban beach in the heart of Tokyo where competition takes place. In 2019, the swimming at the Paratriathlon World Cup was abandoned due to elevated levels of E-coli at the Odaiba Marine Park, but Tokyo organisers have ruled out any change of venue, saying the E-coli levels fall within “agreed limits’’ on most days. Team GB also said on Wednesday that it was confident that the Tokyo waters will be safe. 

"Our athletes have been in that water for test events and training and in competition," Britain’s Chef de Mission, Mark England, said. "We look forward to seeing the triathletes compete there next week.”

Triathlon events are on July 26, 27 and 31, while the marathon swim – a 10km endurance events – is held on August 4-5. The Asian brown bear, meanwhile, is a common sight across Japan, and has been known to attack and even kill local residents. Police had launched a hunt just hours before the opening pitch between Japan and Australia. 

"A guard found a bear inside Azuma Sports Park early in the morning yesterday. We also received similar information this morning," an officer told the AFP news agency. "We couldn’t find or capture the bear, and while there won’t be any spectators at the stadium, we are on alert and searching for the bear around the site." 

Local sports newspaper, Sports Hochi, reported that the entire contingent of Olympic guards had spent the night searching for the creature, blasting music and letting off firecrackers in an effort to flush it out. Fortunately, the softball match went ahead without any interruption, with Japan recording an 8-1 victory. 

Last month, a brown bear sparked a massive search involving police and local hunters in the northern city of Sapporo, which will host the Olympic marathon. The bear mauled a soldier and a pedestrian who was hospitalised after the attack.