A theatre group in Hong Kong has transformed its rehearsal space into a face mask factory to help fight the spread of coronavirus.

Volunteers from the group Nonsensemakers are using their backstage skills to sew reusable face masks for those who cannot access or afford them.

Jo Ngai, a drama lover and founder of the group, came up with the idea with her friend Jessie Han.

The two said they saw the price of surgical masks had "surged threefold" following the outbreak of the virus - officially called Covid-19.

"We think that it is nearly impossible for the ordinary citizens, especially the poor, to buy surgical masks. But face masks are essential amid the outbreak," Ms Han said.

A volunteer helps iron the layers of material into place. Credit: AP

With the help of a group of volunteers they met online, the pair have been working to produce 400 reusable fabric masks.

It is not clear how effective they will be in combating the virus, but the theatre lovers think their triple-layered creations will be an effective defence.

Ms Ngai explained how the masks can be reused and recycled:

"The fabric masks have three layers. The outside layer is made out of cotton, the middle layer is waterproof fabric, and the inside layer is made out of breathable and moist-absorbing cotton.

"If users want more protection, they can cut a surgical mask in half and put the half part into the middle of the fabric mask.

"At the end of the day, you can throw away the surgical mask and wash the fabric mask with soap and water. It can be reused once dry."

The theatre group's rehearsal space has been transformed into a textile factory. Credit: AP

As infections have grown in Hong Kong, thousands have lined up to buy masks resulting in limited supply and rising prices.

Ms Ngai said the group had originally planned to give the handmade masks "to the poor" but production was slow and so they redirected their efforts:

"We decided to give them to the frontline medical workers.

"We wish to express our gratitude to them and so they could use them on their way to work and back from work, but not be used in medical wards."

Thousands of medical workers in Hong Kong went on strike earlier this month, in protest at the reaction of authorities to the outbreak from mainland China.

Travellers on Hong Kong's Mass Transit Railway wear surgical masks amid the outbreak. Credit: AP

Ms Ngai added: "We have never conducted any laboratory test for the masks, but we think in times of desperation, a mask of any source offering some protection is better than nothing."

Regardless of their origin, fabric masks are a good option amid the shortage of industrially produced surgical masks, according to Dr Joseph Tsang - a Hong Kong specialist in infectious diseases.

Dr Tsang said: "It is always better to wear something rather than nothing.

"Regarding the design of this fabric mask, putting a surgical mask into the middle of the mask can help prevent the virus and the mask’s moist absorbing layer can extend the lifespan and effectiveness of the surgical mask."

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Dr Jennifer Rohn, a cell biologist at University College London, said simple surgical masks "are not very good at preventing viral spread".

Masks with a ventilator offer better protection, Dr Rohn told ITV News, but added "viruses can jump" and so washing hands regularly is also advised.

The handmade masks have space to put a surgical mask within the outer fabric layer. Credit: AP

One of the volunteers involved in the project, Jes Cheung, said she wanted to help out despite not knowing how to sew:

"I never met Jo before. But my friend saw this event on Facebook, and I wanted to contribute.

"I don't know how to operate a sewing machine, but I still wanted to come because I know that there are other procedures that I could help with. That's why I am here today.

The group have so far made 400 fabric masks. Credit: AP

The number of coronavirus cases in China has dropped in recent days but the total number of reported cases has reached more than 75,000 in the country since the outbreak begam.

The death toll from the viral pneumonia outside mainland China stands at eight - two people in Hong Kong have died after contracting the virus.