New Delhi  - United States-based Continental Airlines on Wednesday made a formal apology to former Indian president APJ Abdul Kalam for frisking him before boarding its flight from New Delhi in April.

The apology came a day after angry protests in India's Parliament over the "humiliating" treatment meted out to Kalam.

India's Civil Aviation Minister Praful Patel told parliament Tuesday that his ministry had demanded the airline explain the frisking of Kalam in violation of guidelines.

Under domestic protocol, presidents and former presidents are on the VVIP list and are exempted from security checks and searches.

Kalam was subjected to a full body check and asked to remove his footwear by ground security staff of Continental Airlines at the airbridge at the Indira Gandhi International Airport before boarding the flight to the US on April 24 this year.

"Continental Airlines apologizes to the former president of India, Dr APJ Abdul Kalam, for any misunderstanding and/or inconvenience related to the security screening on
21 April 2009," the carrier said in a statement.

"Our intention was never to offend Dr Kalam or the sentiments of the people of India. Continental Airlines takes great pride and is honoured to have flown a respectable leader such as Dr Kalam," the statement said.

"We have tendered a formal apology to Dr Kalam and we sincerely hope he will fly with us again."

The airline said regulations mandated by local authorities such as India's Bureau of Civil Aviation Security and US agencies like the Transportation Security Administration were at times incompatible.

"We hope the respective government authorities resolve these differences at the earliest in order to avoid any recurrence of this situation in the future," the airline said.

Continental Airlines said it had received a show-cause notice from the Indian government on July 20 and would be giving a formal reply.

Kalam, president from 2002 to 2007, is highly popular across India. An eminent nuclear scientist, he is known as India's "missile man" for his work on development of indigenous ballistic missile and space rocket technology.(dpa)