WASHINGTON - FBI Director Christopher Wray defended his agency Thursday against US President Donald Trump’s criticism aimed at discrediting the probe into alleged collusion between his campaign and Russia in last year’s election.

Trump laid into the Federal Bureau of Investigation on Twitter last weekend, accusing its agents of political bias and Wray’s predecessor James Comey, who Trump fired in May, of lying. “Its reputation is in Tatters - worst in History,” Trump wrote of the FBI , at the end of series of tweets about a senior agent who allegedly supported Trump’s Democratic rival Hillary Clinton.

“My experience has been that our reputation is quite good,” Wray told the House Judiciary Committee.

“The agents, analysts and staff of the FBI are big boys and girls. We understand that we will take criticism from all corners. We’re accustomed to that,” he said.

Wray fielded tough questions over whether both last year’s probe into Clinton’s use of classified material on a private email server, and special prosecutor Robert Mueller’s investigation into possible collusion by the Trump campaign with Russian interference, were run by anti-Trump investigators.

Wray acknowledged the controversy over the allegedly pro-Clinton FBI agent who was dismissed as a lead investigator on Mueller’s team - the news which sparked Trump’s weekend anti-FBI tweetstorm.

Agent Peter Strzok also allegedly had a key role in Comey’s July 2016 decision - in the middle of a tense election campaign - to clear Clinton of any crime.

Mueller dismissed Strzok around mid-year from the Russia probe after it surfaced that he had sent pro-Clinton text messages to a colleague, which Republicans say prove his bias in both probes.

But Republicans have hiked up pressure, saying that Mueller’s team, which has already charged four former Trump aides with crimes, was overwhelmingly pro-Clinton.

They noted public records which show that nine out of 16 lawyers under Mueller having donated money to Democratic presidential candidates and none to Trump.

“There are all kinds of people on Mueller’s team who are pro-Clinton,” said Republican Congressman Jim Jordan.

“If you kicked everybody off Mueller’s team who are anti-Trump, I don’t think there would be anybody left.”

Jordan alleged that Strzok, whom he described as the head of counter-intelligence operations at the FBI , had used a “fake news” dossier as evidence last year to obtain a secret national security warrant to spy on senior figures of the Trump campaign.

Wray refused to discuss Strzok, saying his behavior was currently under “outside, independent” investigation by a government inspector general.