WASHINGTON (REUTERS) - Former CIA director under the Obama administration Leon Panetta said on Monday (March 21) that US President Donald Trump should "apologise" to former President Barack Obama over Trump's allegation that Obama "wiretapped" his election campaign.

FBI Director James Comey told a congressional hearing earlier on Thursday that he had seen no evidence to support a claim by Trump that Obama had wiretapped his campaign headquarters in Manhattan's Trump Tower.

Panetta said Trump should move on to other pressing issues in the US, like healthcare and immigration.

FBI Director James Comey also confirmed during his hearing that the agency was investigating possible Russian government efforts to interfere in the 2016 US election including any links between President Donald Trump's campaign and Moscow.

Panetta said the Russia election hacking allegations are a "big deal" worth looking into.

"It's really important that we investigate just exactly what they did, whether there was any collusion involved," Panetta said during the interview at the Bipartisan Policy Center in Washington.