An arrest warrant was issued for Vorayuth last Friday following his failure to meet prosecutors for a decision on his indictment a day earlier.
Immigration Bureau chief Pol Lt Gen Natthorn Phrosunthorn said his office could check people travelling in and out of the country and if Vorayuth re-entered Thailand the system would alert them.
He explained that Vorayuth had left the country before the arrest warrant was issued.
He said Thong Lor police investigators did not ban him from travelling abroad as the case stemmed from recklessness rather than a serious case with criminal intent. Therefore, he said, the Immigration Bureau was not authorised to stop him.