Germany stepped up its criticism of Donald Trump, the US president, a day after Angela Merkel declared that the US and the UK were no longer "reliable partners".

Mrs Merkel, speaking at a conference on sustainable development in Berlin, reinforced Germany’s commitment to tackling climate change and said it was vital not to varnish over differences with allies.

Mrs Merkel did not specifically mention Mr Trump but quoted a 1963 speech by former President John F. Kennedy in Frankfurt, where he told the audience "those who look only to the past or the present are certain to miss the future."

"With change comes insecurity, scepticism ... and, not infrequently, the glorification of the supposedly good old days," Mrs Merkel said. "Particularly in view of the complexity of global contexts, a wish for simple answers spreads.

"But anyone who puts on national blinkers and has no view of the world around him will ultimately get lost."

Sigmar Gabriel, the German foreign minister, criticised Mr Trump's "short-sighted" policies that have "weakened the West" and hurt European interests.

Mr Gabriel said that "anyone who accelerates climate change by weakening environmental protection, who sells more weapons in conflict zones and who does not want to politically resolve religious conflicts is putting peace in Europe at risk".