WASHINGTON • United States President-elect Donald Trump has said his intelligence briefing on allegations that the Russian government was behind a hack of Democratic campaign e-mails has been delayed until the end of the week, and that US officials may need more time to bolster their conclusions.

"The 'Intelligence' briefing on so-called 'Russian hacking' was delayed until Friday, perhaps more time needed to build a case," Mr Trump tweeted on Tuesday night. "Very strange!"

A US official, who has knowledge of the matter and asked for anonymity, said Mr Trump is to be briefed on an intelligence summary on foreign interference in the US presidential election in the next few days. The official said the briefing had not been scheduled for Tuesday.

President Barack Obama last week moved to sanction top Russian intelligence officials over the hacking. The Obama administration also expelled 35 Russian intelligence operatives from the country and restricted access to two Russian diplomatic compounds.

Mr Trump has repeatedly expressed scepticism at the conclusion of intelligence agencies that Russia was behind the hacking and release of e-mails in an effort to damage his campaign opponent, Democrat Hillary Clinton.

Mr Trump yesterday also quoted WikiLeaks founder and fugitive Julian Assange as he questioned the Russians' role in the hacking. "Julian Assange said 'a 14-year-old could have hacked Podesta' - why was DNC so careless? Also said Russians did not give him the info!"

Mr Trump was referring to the hacking of e-mails connected to the Democratic National Committee and Mrs Clinton's presidential campaign chairman John Podesta.

Mr Trump has pledged to improve relations with Russian President Vladimir Putin, whose government has denied it was behind the hacking.

BLOOMBERG, REUTERS