Mahmoud Ahmadi-Nejad said on Sunday that his declared re-election as president of Iran was a “blow to the oppressive system ruling the world” after a weekend in which thousands of protesters clashed with police and rivals demanded a re-run.

Western leaders expressed dismay at the disputed results that awarded a landslide victory to the firebrand incumbent, with Joe Biden, the US vice-president, saying there was “real doubt” about them.