A team of scientists in the US has figured out the compounds in human blood that attract mosquitoes - potentially paving the way for a drug that could mask our tempting flavour.

Mosquitoes' bloodsucking habits make them the deadliest animal on the planet to humans, killing around half a million people every year through diseases including malaria, dengue and yellow fever.

Veronica Jove, one of the lead researchers in the study, which is being carried out at The Rockefeller University in New York City, said: "If mosquitoes weren't able to detect the taste of blood, in theory they couldn't transmit disease."

Only female mosquitos feed on blood, which they need for their eggs to develop, but they survive primarily on nectar.

The researchers used genetically-modified females to see which neurons fired when they tasted blood.

They tricked the mosquitoes into switching from nectar feeding mode to blood feeding mode by offering them a mix of four compounds developed to mimic the flavour of blood.

It contained glucose, sodium chloride, sodium bicarbonate and adenosine triphosphate (ATP) - a compound that provides energy to cells.

A fluorescent tag in the genetically modified insects glowed when a nerve cell was activated, allowing the researchers to track which nerve cells lit up when they were offered different meals.

Only one subset of neurons were activated by blood, including both real blood and the researchers' synthetic mix.

The team believes the investigation could eventually lead to oral mosquito repellents that would interfere with their taste for blood.

The research was published in the journal Neuron.