2016 Rio

US coach claims doping the "biggest threat" to swimming competition at Rio 2016

This follows the surfeit of doping-related controversies in the sport, including allegations this month that Russian anti-doping officials unsuccessfully requested money in return for covering up failed drug tests registered ahead of London 2012.

Particular concerns have been raised in relation to Russian and Chinese swimmers, with world champion Yuliya Efimova and Olympic gold medal winning counterpart Sun Yang among leading athletes to be implicated.

World Health Organization rejects calls to move Rio 2016 over Zika outbreak

In an open letter to the WHO, 150 leading international scientists, doctors and medical ethicists said new findings about the mosquito-borne disease made it "unethical" for Rio 2016 to go ahead as planned.

Representatives of institutions such as Oxford University and Harvard and Yale universities in the United States cite the failure of a mosquito-eradication programme in Brazil, and the country's "weakened" health system as reasons to move or postpone the Games in "the name of public health".

Fake lottery wins and "magic pill" scams connected to Rio 2016 Olympics

According to cybersecurity firm Kaspersky Lab, scammers have been active since early 2015.

As well as fake tickets, they are also thought to be distributing malware-ridden emails and phishing attacks.

"According to our research, the creation of fake sites usually involves well organised, fraudulent, international gangs," said Andrey Kostin, senior web content analyst at Kaspersky Lab.

"They split tasks, so that each small group is responsible for a separate part of the work.