New Delhi, Sept 8 (IANS):  India Tuesday said the United Arab Emirates (UAE) has "apologised" for not declaring the consignment of weapons its China-bound cargo plane was carrying that led to its detention at Kolkata airport, and assured early release of the aircraft will be facilitated.

Indian authorities Sunday detained an UAE Air Force plane that landed in Kolkata from Abu Dhabi on its way to Xianyang, China, after discovering arms and explosives on board.

The military transport plane, the C-130 Hercules, was allowed to land at Kolkata to refuel, but it did not declare its cargo.

The interrogation of the pilot and nine crew members of aircraft, however, revealed that the flight was carrying arms, ammunition and explosives. The detention of the aircraft, that entered its third day Tuesday, was threatening to turn into a diplomatic row till the UAE authorities apologised.

Clearing the air, the external affairs ministry said here Tuesday that the confusion arose as no mention of the arms and ammunition was made at the time of initial application for landing.

The authorities at Kolkata airport, therefore, detained the aircraft for further investigation, the ministry said.

"Accordingly, after the concurrence of the pilot-in-command of the aircraft, the custom Officials entered the aircraft to inquire about the nature of cargo," it said in a statement.

"The UAE authorities both here and in Abu Dhabi have since formally regretted the omission in clearly indicating items carried by the aircraft and have described it as a technical error," the ministry said.

Captain of the flight, Major Ibrahim Alshamsei has filed a declaration to the customs stating that the flight was carrying arms/ammunition/explosives. They have also provided details about the cargo which consists of combat missiles, the ministry said.