Doha-based Al Jazeera reported that Turkish troops had arrived in Qatar on Sunday. Military sources in the region told Reuters no new Turkish military unit had been sent to Qatar and a unit already present there was taking part in the drills.
Al Jazeera posted a video on its website of armoured personnel carriers moving through streets.
Turkey's parliament on June 7 fast-tracked legislation to allow troops to be deployed to a military base in Qatar that currently houses about 90 Turkish soldiers.
Turkey set up the base, its first such installation in the Middle East, as part of an agreement signed in 2014.
The Turkish forces conducted their first training at Tariq bin Ziyad military base on Sunday, al Jazeera said, citing the ministry, saying the drills had been long planned.