Officials did not search President Evo Morales's presidential jet for fugitive US intelligence contractor Edward Snowden, Fischer said – seeking to defuse a diplomatic tussle over the incident.
One airport officer did board the aircraft on Tuesday to find out why it had landed in Vienna reporting technical problems, but "there was no formal inspection", the Austrian president told Kurier newspaper.
Fischer's comments, published on Sunday, appeared aimed at untangling contradictory accounts of how Bolivia's president was treated as he flew home from a conference in Moscow last week.
Bolivia protested after several European countries refused to allow the aircraft to pass through their airspace, amid speculation Morales was taking Snowden to Latin America.
Diplomatic tensions heightened after the plane landed in Vienna and Austrian officials initially said they got official permission to inspect the aircraft for Snowden, who is wanted for leaking details of US surveillance programmes. Bolivia insisted no such inspection took place.
"Someone from the airport staff sought out the aircraft or the pilot after landing to inquire about the nature of the technical problem," Fischer was quoted as saying.
"The Austrian official was advised that the defect was already fixed, and saw on this occasion that the plane was empty … He did not look under the seats. There was no formal inspection, but no other people were found on board," Fischer added.
'There was no search'
Pressed on whether that meant Austrians had not searched the plane, he said:
"There was no search in the forensic sense. There was also no reason to under international law. The plane of a president belongs to 'his territory' and cannot be searched readily."
Snowden is believed to be still holed up in the transit area of Moscow's Sheremetyevo International Airport and has been trying to find a country that would give him sanctuary since he landed there from Hong Kong on June 23.
Bolivia on Saturday formally offered Snowden asylum, joining leftist allies Venezuela and Nicaragua in defiance of Washington. – Reuters