The personnel were sent back on Tuesday night after instructions in this regard were issued by the Centre, an official release said on Wednesday.
Officials of the air force station in Chennai had sought police protection for these personnel. Police conveyed this information to the chief minister.
The chief minister immediately asked the air force officials to get in touch with the Centre, asking them to send the airmen back to their country. Accordingly, the Centre issued instructions.
Last year, a similar incident occurred when some Sri Lankan army men who arrived at Coimbatore for training with Central Reserve Police Force were sent back to their country, following demands from political parties that army personnel from Sri Lanka should not be trained in India, as it would be used against Tamils in Sri Lanka.