Two more senior Democrats have called for an investigation into a share-buying spree by two fossil fuel billionaires with close ties to the Trump administration, after a Guardian investigation raised questions about potential wrongdoing.

Robert Pender and Michael Sabel, the founders and co-chairs of Venture Global, a liquefied natural gas (LNG) company headquartered in Virginia, bought more than a million shares worth almost $12m each in March. The trades took place just days after a meeting with senior White House officials, who then issued a key regulatory permit that helped expand the company’s business in Europe.

Ron Wyden, the ranking member of the Senate finance committee and a member of the energy and natural resources committee, said the transactions should be investigated, drawing parallels with previous Trump administration controversies.