London, Apr 5 (IANS): UK Prime Minister Boris Johnson is due to unveil a new traffic light system for international travel amid the Covid-19 pandemic after May 17.

Johnson, who is expected to speak on Monday evening, will announce a red, amber and green system for residents in England who want to go on holiday abroad, reports dpa news agency.

Each country will be given a rating which determines whether or not travellers will need to go into quarantine on their return, a statement from Johnson's office said.

"Green" countries mean residents will have to take coronavirus tests before and after departure but will not have to quarantine upon returning to England.

"Amber" or "red" countries mean citizens would have to take tests and go into quarantine upon their return.

The system will be based on how many people have been vaccinated in each country, the rate of infection, emerging variants of the coronavirus and the country's access to "reliable scientific data and genomic sequencing".

"It is too early to predict which countries will be on which list over the summer," a spokesperson said.

"Our decisions will be driven by the evidence available at the time, as such, we continue to advise people not to book summer holidays abroad."

It is not clear how vaccines will be taken into consideration for the system but Johnson is expected to confirm this later on Monday.

While the traffic light system is just for England, the British government is said to be in talks with the devolved governments in Scotland, Wales and Northern Ireland.