WASHINGTON, March 20 (Xinhua) -- The White House on Monday defended President Donald Trump's claim that his predecessor Barack Obama had ordered wiretapping Trump Tower and played down FBI's probe into Russian election meddling.

"There's still a lot of information that needs to be discussed," White House Press Secretary Sean Spicer said about Trump's wiretapping accusation at his daily press briefing, soon after FBI chief James Comey told a congressional hearing Monday that he had no information supporting the president's wiretapping claim.

"It's clear that nothing has changed," Spicer also commented on Comey's first public confirmation that the Trump campaign has been under FBI investigation since July, stressing that there is no evidence of collusion between the Trump campaign and Russia during the election.

FBI "is investigating the alleged Russian government's efforts to interfere in the 2016 presidential election and that includes investigating the nature of any links between individuals associated with the Trump campaign and the Russian government and whether there was any coordination between the campaign and Russia's efforts." Comey testified at the Capitol Monday morning.

"I cannot say more about what we are doing and whose conduct we are examining." Comey said, citing that the probe is classified and ongoing.

The Russian government has also denied the accusations.

"With respect to the president's tweets about alleged wiretapping directed at him by the prior administration, I have no information that supports those tweets and we have looked carefully inside the FBI." Comey told lawmakers.

Ahead of the congressional hearing, Trump tweeted: "James Clapper and others stated that there is no evidence Potus colluded with Russia, This story is FAKE NEWS and everyone knows it!" Clapper is the former national intelligence director.

In another tweet, Trump asked: "What about all of the contact with the Clinton campaign and the Russians? Also, is it true that the DNC would not let the FBI in to look?"

On March 4, Trump claimed in a tweet storm that Obama had Trump Tower wiretapped before his election victory, offering no evidence.

Hours after Trump's tweets, Obama's spokesman said Trump's wiretapping accusation is "simply false."

"There was not a physical wiretap of Trump Tower", Republican Devin Nunes, chairman of U.S. House Select Intelligence Committee, said at the beginning of the hearing on Monday.

"However, it's still possible that other surveillance activities were used against President Trump and his associates," said Nunes.