The Export-Import Bank gave final approval this week to the controversial low-interest $200 million loan to an Australian airline partly owned by publisher Rupert Murdoch, but the loan still faces a hurdle in the Senate.

The Senate Banking Committee, now controlled by Republicans who were particularly critical of the loan last spring, has a month to decide whether to approve or scuttle the loan. The loan comes under scrutiny only days after President Reagan called for a dramatic reduction in Ex-Im's lending authority.

The loan to Murdoch was attacked as politically inspired last spring when it was revealed that Ex-Im gave tentative approval shortly after the Australian financier had lunch on Feb. 26 with President Carter at the York Post endorsed Carter in the New York primary election.

The bank is an independent government agency to promote U.S. exports by low-interest loans to foreign buyers.

The 8 percent loan was to enable Murdoch's Ansett Transport Industries in Australia to buy planes manufactured by Boeing Co. rather than competitive airliners manufactured by a European consortium.

The loan was sharply criticized by members of the Senate Banking Committee, especially by the Republicans, than in the minority. Sen. H. John Heinz III (R-Pa.) claimed that the Carter-appointed Ex-Im chairman, John L. Moore Jr., withered under Murdoch's high-pressure business tactics.

But after an investigation, the committee was unable to find "documented evidence" of political impropriety in the loan.

Now, the Republicans will take another look at the loan. It seems unlikely, however, that the Republicans would block the loan, an act that could have serious repercussions in U.S.-Australia relations.

However, Republican staff economist Paul Freedenberg said: "We're on the record of being opposed to the loan, so it's certainly going to get close scrutiny."