Media playback is unsupported on your device Media caption Professor Mark Post of Maastricht University explains how he and his colleagues made the world's first lab-grown burger

The world's first lab-grown burger is to be unveiled and eaten at a news conference in London on Monday.

Scientists took cells from a cow and, at an institute in the Netherlands, turned them into strips of muscle which they combined to make a patty.

Researchers say the technology could be a sustainable way of meeting what they say is a growing demand for meat.

Critics say that eating less meat would be an easier way to tackle predicted food shortages.

BBC News has been granted exclusive access to the laboratory where the meat was grown in a project costing £215,000.

Prof Mark Post of Maastricht University, the scientist behind the burger, said: "Later today we are going to present the world's first hamburger made in a lab from cells. We are doing that because livestock production is not good for the environment, it is not going to meet demand for the world and it is not good for animals".

But Prof Tara Garnett, head of the Food Policy Research Network at Oxford University, said decision-makers needed to look beyond technological solutions.

"We have a situation where 1.4 billion people in the world are overweight and obese, and at the same time one billion people worldwide go to bed hungry," she said.

"That's just weird and unacceptable. The solutions don't just lie with producing more food but changing the systems of supply and access and affordability so not just more food but better food gets to the people who need it."

Image caption An independent study found that lab grown beef uses 45% less energy than the average global representative figure for farming cattle. It also produces 96% fewer greenhouse gas emissions and requires 99% less land.

We are doing this because livestock production is not good for the environment, it is not going to meet demand for the world and it is not good for animals" Prof Mark Post, Maastricht University

Stem cells are the body's "master cells", the templates from which specialised tissue, such as nerve or skin cells develop.

Most institutes working in this area are trying to grow human tissue for transplantation, to replace worn out or diseased muscle, nerve cells or cartilage.

Prof Post wants to use similar techniques to grow muscle and fat for food.

This might sound a little creepy to some - but Prof Post is no Dr Frankenstein. He's normal and likeable; when he talks about his project there is a gleam in his eye.

He starts with stem cells extracted from cow muscle tissue. In the laboratory, these are cultured with nutrients and growth promoting chemicals to help them develop and multiply. Three weeks later, there are more than a million stem cells which are put into smaller dishes where they coalesce into small strips of muscle about a centimetre long and a few millimetres thick.

These strips are collected into small pellets which are frozen. When there are enough, they are defrosted and compacted into a patty just before being cooked.

The scientists have tried to make the meat - which is initially white in colour - as authentic as possible. Helen Breewood, who is working with Prof Post, makes the lab-grown muscle look red by adding the naturally occurring compound myoglobin.

Media playback is unsupported on your device Media caption How would lab grown meat go down? The BBC's Pallab Ghosh asked the clientele of Duggie's Dogs hot dog restaurant in downtown Vancouver

A lot of people consider lab-grown meat repulsive. But if they consider what goes into producing normal meat in a slaughter house I think they would also find that repulsive Helen Breewood, Project scientist and vegetarian

"If it doesn't look like normal meat, if it doesn't taste like normal meat, it's not... going to be a viable replacement," she told me.

Currently, this is a work in progress. The burger to be revealed on Monday will be coloured red with beetroot juice. The researchers have also added breadcrumbs, caramel and saffron, which will add add to the taste.

At the moment, scientists can only make small pieces of meat; larger ones would require artificial circulatory systems to distribute nutrients and oxygen.

Prof Post said initial sampling suggests the burger will not taste great, but he expected it to be "good enough". The meat will be tasted a team which includes Josh Schonwald, a food writer from Chicago, and Richard McGowan, a chef from Cornwall.

Animal suffering

Ms Breewood is a vegetarian because she believes meat production to be waste of resources, but says she would eat lab-grown meat.

Image caption The aim is to make the lab-grown burger look and taste like the real thing. But it isn't there yet.

"A lot of people consider lab-grown meat repulsive at first. But if they consider what goes into producing normal meat in a slaughter house I think they would also find that repulsive," she said.

In a statement, animal welfare campaigners People for the Ethical Treatment of Animals (Peta) said: "[Lab-grown meat] will spell the end of lorries full of cows and chickens, abattoirs and factory farming. It will reduce carbon emissions, conserve water and make the food supply safer."

But food writer Sybil Kapoor said she felt "uneasy": "The further you go from a normal, natural diet the more potential risks people can run in terms of health and other issues," she said.

The latest United Nations Food and Agriculture Organization report on the future of agriculture indicates that most of the predicted growth in demand for meat from China and Brazil has already happened and many Indians are wedded to their largely vegetarian diets for cultural and culinary reasons.

So lab grown meat might turn out to be a technological solution in search of a problem.

Follow Pallab on Twitter @bbcpallab