Their leaders have conducted informal discussions before, but the event on Tuesday in the central Russian city of Yekaterinburg will mark their first formal gathering, officials said.

• 四国领导人此前已进行过非正式会谈，星期二在俄罗斯中部城市叶卡捷琳堡举行的会谈将标志着他们的首次正式会晤，有官员表示。