A CBI team on Tuesday raided the Airports Authority of India office in Thiruvananthapuram over royalty evasion in ground handling services, reports said.

The details of the day-long raid, which were kept as a closely guarded secret, came to light only one day after it took place.

The AAI office has been under CBI scanner for the past six months, IANS reported. The raid comes after allegations that the ground-handling agencies have not been paying royalty to the Airport Authority of India.

The CBI has also seized the documents related to ground-handling charges, sources said.

Ground-handling services include check-in, handling baggage and cargo, loading and unloading of food items on aircraft and ferrying passengers to and from planes.

When asked about the raid, AAI official George Tharakan refused to respond on the matter, reported IANS.

Earlier, the CBI had collected a detailed statement of ground-handling charges from national carrier Air India as well as international airlines that they have paid to the agencies since 2012.

Currently, there are two ground-handling agencies, including a joint venture of the national carrier, that operate at the Thriuvananthapuram International Airport.