Scientists have unveiled plans to genetically engineer a lethal strain of bird flu to understand how it could mutate in nature and trigger a catastrophic pandemic.

The H7N9 bird flu virus has infected more than 130 people and killed 43 since it emerged in China in March. The first strong evidence that the virus can spread from person to person appeared in the British Medical Journal this week.

While the closure of poultry markets has brought the outbreak under control, researchers fear infections may rise again in the winter.

As long as the virus is in circulation, it can transform into a strain that is more dangerous, through natural mutations or by mixing with other strains of bird flu in animals such as cattle and pigs.

Scientists outlined their plans to work with the virus in joint letters to the journals Nature and Science on Wednesday. The 22 signatories include Ron Fouchier at Erasmus Medical Centre in Rotterdam and Yoshihiro Kawaoka at the University of Wisconsin-Madison. Work by the scientists on another strain of bird flu sparked security fears last year.

The controversial experiments are expected to make the H7N9 virus more virulent and increase its ability to spread between people. But researchers argue the work is crucial for public health because it will drive research into drugs and vaccines, and help identify dangerous mutations to watch out for in the wild.

"The pandemic risk rises exponentially should these viruses acquire the ability to transmit readily among humans," the authors write. They go on to describe a raft of experiments that should reveal how the virus might adapt to humans, spread more rapidly, become more virulent and develop resistance to frontline drugs.

Scientists already track mutations in bird flu viruses found in patients, but this kind of surveillance does not give health authorities time to respond if they find a pandemic strain. The proposed experiments should give scientists early warning of the kinds of mutations that could spark a pandemic.

The work will be done in high-security laboratories to minimise the risk of the modified viruses escaping and causing precisely the kind of devastation the research aims to prevent.

Last year, the US government's biosecurity watchdog raised the alarm over similar work on another bird flu virus called H5N1. The panel feared that details of the experiments by Fouchier and Kawaoka could help terrorists create lethal viruses as bioweapons.

Their papers were eventually published, but tougher review procedures have since been brought in by US authorities on "dual use research", along with updated guidelines to ensure the work is done under tight security.

Fouchier told the Guardian that he and the other scientists announced their plans to be as open as possible about their research. Much of the work can continue under European funding without further scrutiny.

Wendy Barclay, a virologist at Imperial College London, said it would be "ludicrous" not to do the experiments. "They allow us to see how the virus might evolve and what we can expect from nature," she said. "This type of work is like fitting glasses for someone who can't see well – without the glasses the vision is blurred and uncertain, with them you can focus on the world and deal with it a lot more easily."