A Singapore Airlines (SIA) plane was about 90km or some 10 minutes away, when a Malaysia Airlines jet was shot down over eastern Ukraine last month.
Earlier reports had put SQ351 from Copenhagen, Denmark at about 25km away from MH17
Transport Minister Lui Tuck Yew in Parliament on Monday confirmed that the plane was actually about 90km away and added that there were no flight restrictions above 32,000ft over the particular airspace at the time.
MH17 was flying from Amsterdam, Netherlands to Kuala Lumpur when it was blown out of the skies while flying over eastern Ukraine where pro-Russian rebels are fighting government forces.
"No national authorities, no regional aviation bodies, nor ICAO (International Civil Aviation Organisation) has provided any advisories to avoid that part of the Ukrainian airspace" Mr Lui said.
Apart from SIA, many other carriers including Air India, Emirates and Lufthansa were flying over the same skies before the incident on July 17.
Cutting through Ukranian airspace is the most optimal route for airlines flying between Europe and the Middle East, South Asia and South-east Asia, Mr Lui said.
"It was therefore being regularly and heavily utilised by many airlines" he said.
As for carriers flying between Europe and North Asia, there is usually no need to use Ukrainian airspace.
Following the crash, several carriers including Australia's Qantas, British Airways and airlines from South Korea said they do not fly over Ukraine.
Ultimately, airlines make route decisions based on many factors, including advisories issued by countries with regard to their airspace, Mr Lui said.
He noted that in other parts of the world, SIA has avoided flying over conflict zones although the skies were open and other carriers were operating flights.
Since the MH17 incident, the Civil Aviation Authority of Singapore (CAAS) has asked Singapore carriers to review their risk assessment of flying over conflict areas, Mr Lui said.