Most members of a U.S. National Park Service advisory board, appointed while Barack Obama was president, have resigned after saying they were ignored by President Donald Trump's administration, the panel chairman said Tuesday.

The National Park System Advisory Board, whose creation was authorized by the U.S. Congress in 1935, is tasked with advising on matters such as the designation of historic and natural landmarks.

Seven of the panel's 10 members have submitted their resignations, Tony Knowles, who chaired the panel and was among those quitting, said by telephone.