New claims surrounding Bronwyn Bishop's expensive charter travel have taken the scandal to "the next level" and the Prime Minister can no longer ignore demands for accountability, Opposition Leader Bill Shorten says.

The federal Speaker spent more than $6000 of taxpayers' money to charter a luxury aircraft to travel to the NSW south coast just two weeks after her infamous helicopter ride in 2014, News Corp reported. It is understood she attended several events, including Liberal fundraisers, in the towns of Nowra and Berry on November 22.

Under pressure: Federal Speaker Bronwyn Bishop. Credit:James Brickwood

But Mrs Bishop's office is refusing to reveal whether the Nowra charter was arranged by the same political lobbyist, Andrew Gibbs, who paid to organise the now notorious $5000 helicopter charter from Melbourne to Geelong on November 5.