Forty countries including Japan and the European Union have agreed on a draft U.N. regulation for advanced emergency braking systems (AEBS) for new cars and light commercial vehicles from early 2020, a U.N. agency said on Tuesday.

The new regulation, compulsory for countries that adopt it at a June session, will impose strict and harmonized requirements for automatic braking at speeds of up to 60 km per hour to save lives, especially in urban settings, the U.N. Economic Commission for Europe (UNECE) said.

"It activates the brake to stop a crash and that's it ... It will not drive, it will brake," UNECE spokesman Jean Rodriguez told a briefing. There will be no obligation to retrofit older vehicles, he said.

Japan and the EU have said the new AEBS system will become mandatory, representing some 4 million and 15 million new cars respectively each year, the UNECE statement said.

More than 9,500 fatalities were recorded in car crashes in cities in the EU in 2016, 40 percent of them pedestrians, it said.

The United States, China and India - which have huge domestic carmakers - are not part of the original 1958 agreement on which the latest regulation builds, Rodriguez said.