Members of a US House oversight committee grilled witnesses over the possibility that foreign powers that donated to the Clinton Foundation expected favours in return, a tactic also known as "pay-to-play."

Last week, committee member Congressman Mark Meadows said the panel had received hundreds of pages of documents revealing that donors to the Clinton Foundation may have been promised benefits while Hillary Clinton served as US secretary of state from 2009-2013.

"When you have these foreign governments making massive donations to the foundation… I think it is a fair question to ask what were they [donors] expecting in return," Judicial Watch President Tom Fitton told the House committee on Thursday.

Fitton, whose watchdog group was instrumental in getting the State Department to release scores of Clinton’s emails related to the private server scandal, said he believes there is evidence that indicates the Clinton Foundation may have been protected by the Justice Department. 

Meadows during the hearing said Clinton Foundation donations plunged after Hillary Clinton lost the 2016 presidential race, which could reflect that "pay to play" activities were going on before the election.

US Attorney John Huber, the prosecutor appointed to probe the Clinton Foundation, did not even show up to the hearing to the chagrin of Meadows.

In 2015, the International Business Times reported that Clinton, when she was top US diplomat, may have helped foreign states who donated to the foundation to secure multimillion-dollar arms deals. 

In August of 2016, Judicial Watch released 725 pages of documents purporting to show Clinton Foundation staff peddling access to Secretary Clinton.

During her time in office, State Department telephone records showed a disproportionate number of incoming calls from Clinton Foundation staff. US State Department spokesman Mark Toner told reporters that there was "no impropriety" involved regarding these calls and Clinton’s close ties to the foundation and its donors.

Judicial Watch is a conservative watchdog group whose founders and associates have been filing lawsuits against the Clintons for well over two decades.