Bird flu has killed one person in China, as new cases of the virus have been confirmed in six people.

The demise is the latest in a surge of deaths from bird flu infections in China. At least 162 fatalities have been reported since October 2016: a four-fold increase from the same period in 2015-16. According to the World Health Organization (WHO) data, the number of infections is the highest seen since 2013.

Martin Taylor, from WHO's China office, said that January saw a record number of deaths linked to H7N9.

The cases of H7N9 bird flu were reported to the authorities in Hunan at the end of March, leading to poultry markets in Sichuan, Hunan and Zhejiang being closed down, China's state news agency Xinhua reported. The ban in Hunan's capital of Changsha will last until 7 April.

In March, an outbreak in a farm led to 29,760 birds being infected. More than 170,000 birds around the country were culled.

The US Centres for Disease Control's Influenza Risk Assessment Tool (IRAT), rates the current H7N9 outbreak in China as having "moderate-high" risk of becoming a pandemic – the highest rating given to any influenza outbreak the public health body is monitoring.

Speaking to CNN, Taylor said that the cause of the sudden increase in cases was unknown.

"Factors could be an earlier start to the flu season and also a higher rate of infection among poultry," Taylor said.

However, Taylor said there was "no evidence of sustained human-to-human transmission", and the virus was under control.

The outbreak of bird flu in China has led to the British government instructing anyone keeping poultry to follow strict biosecurity measures, including keeping birds indoors. The measures apply to both domestic foul keepers and industrial farms.

WHO's guidance on H7N9 describes the virus as being dangerous as "most patients... become severely ill". However, the "virus does not appear to transmit easily from person to person, and sustained human-to-human transmission has not been reported".

There is no vaccine for H7N9 currently available, so the best way to prevent infection is to avoid exposure.

WHO estimates that annual epidemics of influenza result in 3-5 million cases of "severe illness" among people in high-risk groups, and about 250,000-500,000 deaths.