US to probe FBI 'election spying'

Donald Trump. Pics/AFP

The US Department of Justice has said it will investigate whether the FBI spied on Donald Trump's presidential campaign for political motives, following the US president's call for an inquiry.

"If anyone did infiltrate or surveil participants in a presidential campaign for inappropriate purposes, we need to know about it and take appropriate action," Deputy Attorney General Rod Rosenstein said in a statement late on Sunday.

Trump had demanded that the Justice Department look into possible infiltration or surveillance by the FBI or the DOJ itself of his 2016 campaign, stressing that it was essential to probe if someone from his predecessor Barack Obama's administration had ordered such a request.

"I hereby demand, and will do so officially tomorrow, that the Department of Justice look into whether or not the FBI/DOJ infiltrated or surveilled the Trump Campaign for Political Purposes - and if any such demands or requests were made by people within the Obama Administration!," the US president said on Twitter on Sunday.

The probe comes amid an ongoing investigation, headed by Special Counsel Robert Mueller, into alleged collusion between the Russian government and Trump's 2016 election campaign.

In a series of tweets on Sunday, Trump criticised Mueller's investigation, calling it a "witch-hunt" and asserting that it had not found any collusion with Russia.

On May 17, Mueller was appointed by the US Justice Department to look into possible Russian interference into the 2016 US elections, which Trump won. So far, the Mueller team has indicted a total of 22 people and companies.