Former president George W Bush has issued a thinly veiled attack on Donald Trump as he criticised the “casual cruelty” and “conspiracy theories” in modern politics.

The former Republican leader warned that “bullying and prejudice in our public life sets a national tone” that left young Americans lacking role models.

Mr Bush also issued a clear rejection of white supremacists, saying that such views were tantamount to “blasphemy against the American creed”.

The intervention did not mention Mr Trump by name but took on issues that the US president has been criticised over in recent months.

Mr Trump has been accused of not condemning white supremacists strongly enough, making incorrect statement about predecessors and attacking colleagues on Twitter.

The speech marked a rare appearance for Mr Bush, who has tended to avoid public statements despite expressing unease with Mr Trump when he ran for president.