After weeks of waiting, US President Donald Trump's administration on Monday cleared the way for President-elect Joe Biden to transition to the White House, giving him access to briefings and funding even as Trump vowed to continue fighting the election results.

The US federal agency that must sign off on the presidential transition told President-elect Joe Biden on Monday that he can formally begin the hand-over process.

The Trump campaign's legal efforts to overturn the election have almost entirely failed in key battleground states, and a growing number of Republican leaders, business executives and national security experts have urged the president to let the transition begin.