ASTANA. KAZINFORM - Already hit by recession and political turmoil, Brazil has come under more pressure as 150 health experts called for the Olympics in Rio de Janeiro to be postponed or moved because of the Zika epidemic.

In an open letter to the World Health Organisation, the signatories, who included a former White House science adviser, said the current plans for the Games needed to be revised "in the name of public health".

The open letter cited growing scientific studies that suggest the Zika virus is responsible for birth defects, including microcephaly. In rare cases, it can also cause Guillain-Barré syndrome, a neurological disease that results in temporary, and sometimes fatal, paralysis.

The experts fear that these defects could spread more rapidly around the world as a result of an influx of Olympic visitors to Rio, which has a high incidence of Zika cases.

Their warning came as the Olympic torch made its way around Latin America's largest country, which has already passed the 100-day countdown to the opening ceremony.

"The fire is already burning, but that is not a rationale not to do anything about the Olympics," said Amir Attaran, a professor at the University of Ottawa who is one of the letter's authors. "It is not the time now to throw more gasoline on to the fire."

Earlier this month, Attaran published a commentary in the Harvard Public Health Review calling for the Olympics to be cancelled or relocated. He noted that Rio de Janeiro has recorded 26,000 suspected Zika cases - the highest of any state in Brazil - and has an incident rate of 157 cases for 100,000, the fourth highest in the country. "What is proposed is to bring half-a-million Olympic visitors into the heart of the epidemic," he told the Guardian. "But for the Games, would anyone recommend sending an extra half-a-million visitors into Brazil right now?"

In the latest open letter he is joined by experts from more than two dozen countries who specialise in public health, bioethics and pediatrics.

Their appeal will cause a fresh headache for Brazilian government officials and Olympic organisers, who have repeatedly insisted the Games can go ahead safely as long as athletes and visitors smother themselves in insect repellent to minimise the risks from the mosquito-borne disease.

The government says it has the situation under control thanks to the biggest military mobilisation in Brazil's history: 220,000 army, navy and air force personnel have been called into action, as well as 315,000 public officials.

The World Health Organisation issued a global health emergency about Zika in February, but it has not called for travel restrictions beyond advising pregnant women not to travel to affected areas, such as Rio de Janeiro. In a press conference in the Olympic city earlier this year, a WHO team lead by director Margaret Chan said the risks should be lower in August, which is winter for Brazil and has a far lower prevalence of mosquito borne diseases.

The open letter warns that WHO may be affected by a potential conflict of interest because of its decades-long collaboration with the International Olympic Committee. It noted that the memorandum between the two global organisations, which was last affirmed in 2010, has never been made public.

"WHO cannot credibly assess the public health risks of Zika and the Olympics when it sets neutrality aside," the letter claims.

Some athletes are uneasy. Heptathlon Olympic champion Jessica Ennis-Hill said said she is considering a delayed arrival in Brazil before the Rio Olympics because of risks posed by the Zika virus

The USA swimming team has relocated its pre-Olympic training camp from Puerto Rico to Atlanta.