Updated: 5:23 p.m.

Missouri Republicans called Tuesday for Sen. Claire McCaskill to release income tax records related to her family’s ownership of a private aircraft that she has used for official Senate travel.

In a conference call with reporters, Missouri Republican Party Executive Director Lloyd Smith said the state party would file an amended complaint to the Senate Ethics Committee, asking the panel to review McCaskill’s use of the plane for two political events.

Missouri Republicans filed a similar complaint earlier this month following a media report that McCaskill had used official funds to pay for fuel and other costs related to her use of the plane — which is owned by her husband via a limited liability corporation — for Senate-related duties and at least one political event.

McCaskill, who is up for re-election in 2012, paid the U.S. Treasury $88,000 after Politico first reported those payments.

In a conference call Monday, McCaskill announced that she and her husband had failed to pay $287,000 in property taxes on the private aircraft and said the taxes would be paid immediately. McCaskill also announced that her husband intends to sell the aircraft.

According to Smith, those property taxes have since been paid with a $320,000 check from Sunset Cove Associates, the limited liability company owned by McCaskill and her spouse that chartered the flights. The plane is owned by another company, Timesaver, which is listed as belonging to McCaskill’s husband on her annual financial disclosure report.

A McCaskill spokeswoman denied Smith’s statement and said the Senator paid the outstanding taxes with four checks totaling approximately $287,000. The aide said the check was written from a Sunset Cove account. 

Smith called on McCaskill to release the income tax records of both companies, citing McCaskill’s statements that she did not benefit financially from the official funds used to pay for the chartered flights.

“Missourians are looking at this as a breach of trust,” Smith said. “We’re calling on Claire McCaskill to release the tax returns of both … Sunset Cove and Timesaver.”

McCaskill is a top target for defeat by the GOP in 2012, when she will face her first re-election test.

Two Republicans are already in the race to challenge McCaskill: former state Treasurer Sarah Steelman and 2010 House candidate Ed Martin. But Former Ambassador to Luxembourg Ann Wagner and Rep. Todd Akin are also exploring joining the race.

Asked whether interest in challenging McCaskill has increased in recent days, Smith said: “Let’s just say that there is a heightened awareness of what’s going on in the press with Claire McCaskill’s problems … and we are having a lot interest in this U.S. Senate race.”