Attorney general Jeff Sessions has rebuffed calls from Republicans to have a new special counsel investigate federal law enforcement’s alleged bias and surveillance abuses.

In a letter to a trio of top Republicans, Mr Sessions said the Justice Department’s inspector general was investigating whether officials had complied with the US Foreign Surveillance Court in seeking permission to eavesdrop.

“We understand that the Department is not above criticism and it can never be that the Department conceals errors when they occur”, Mr Sessions said.

The attorney general did not completely rule out the possibility of appointing a special counsel, saying US Attorney John Huber was leading an internal investigation and would ultimately recommend “whether any matters merit the appointment of a Special Counsel”.

Prominent Republican legislators had asked Mr Sessions to appoint a special counsel, warning in a letter of “evidence of bias, trending toward animus, among those charged with investigating serious cases” at the FBI and the Department of Justice.

They also echoed allegations that federal officials relied on opposition research in seeking authority to surveil Carter Page, a former associate of Donald Trump.

Republicans have said the FBI and the Justice Department declined to reveal their application to spy on Mr Page drew on intelligence gathered by Christopher Steele, a former spy funded by the Democratic National Committee and Democrat Hillary Clinton’s campaign – an assertion that Democrats and law enforcement officials have called inaccurate.

That push has come as special counsel Robert Mueller investigates Russian interference in the 2016 presidential election and potential coordination between the Trump campaign and Russia.

Donald Trump has blasted the probe as a politically weaponised “witch hunt” compromised by biased career officials at the Justice Department and the FBI, and he has been adamant that there was no collusion between his campaign and Russia. Mr Mueller has so far indicted multiple former Trump campaign aides.

Earlier this year Mr Trump lashed out at Sessions for leaving the matter of potential surveillance abuse to the inspector general, saying in a tweet that the decision was “DISGRACEFUL”! Mr Sessions responded with a statement saying “As long as I am the Attorney General, I will continue to discharge my duties with integrity and honour”.