Thousands of French pensioners marched through Paris and other cities in protest over higher social security taxes on Thursday, in a warning to President Emmanuel Macron whose popularity is falling in a key voter constituency.

The ebbing support for Macron among retired workers was a factor in the by-election defeat his party suffered last month, just eight months after winning the seat, underlining the challenges he faces with no traditional power base.

Pensioner discontent is a delicate issue for the former investment banker: France has some 15 million pensioners who typically vote in higher numbers than others.