Kazakhstan said on Monday it had not detected any "unsanctioned use" of its air space by any planes on March 8, making it unlikely that a missing Malaysia Arlines jetliner could have been diverted along a northern route via Thailand.
Malaysia Airlines MASM.KL Flight MH370, which vanished with 239 people aboard, could hypothetically have reached the Central Asian nation's air space, but it would have been detected there, the Kazakh Civil Aviation Committee said in a detailed statement sent to Reuters.
"Even if all on-board equipment is switched off, it is impossible to fly through in a silent mode," said the statement signed by the committee's deputy head Serik Mukhtybayev. "There are also military bodies monitoring the country's air space."
Malaysia Airlines planes had made nine regular flights to and from Europe over Kazakhstan's territory on March 8, Mukhtybayev said.
"Even hypothetically thinking, before reaching Kazakhstan's territory this plane would have had to fly over other countries along its route, where the flight zone is also closely monitored, so we would have received information from these countries," he added.
Malaysia Airlines chief executive Ahmad Jauhari Yahya said on Monday that it was unclear exactly when one of the plane's automatic tracking systems had been disabled, appearing to contradict the weekend comments of government ministers.
Suspicions of hijacking or sabotage had hardened further when officials said on Sunday that the last radio message from the plane - an informal "all right, good night" - was spoken after the system, known as "ACARS", was shut down.