NEW DELHI: Former Union defence minister

passed away at the age of 88 on Tuesday morning following a prolonged illness, his family sources said.

Fernandes was suffering from Alzheimer's disease. Recently, he contracted swine flu, they said.

Fernandes held the defence ministry portfolio from 1998 to 2004 under the Atal Bihari Vajpayee-led NDA government. Apart from defence, he also held the portfolios of communications, industry and railways under various governments.

As a defence minister, Fernandes oversaw the Pokhran nuclear tests of 1998 and the Kargil war in 1999. He was also famous for taking frequent trips to the Siachen glacier to look after the well being of the soldiers deployed there and providing facilities such as snow scooters to them cutting down the bureaucracy of his ministry.

He was a key member of the Janata Dal and later founded the Samata Party in 1994, which later merged with Janata Dal (United).

Fernandes was a senior member in Morarji Desai's cabinet when the Janata Party took office in 1977. He also held the portfolio of Union railways minister from 1989 to 1990 under the leadership of the then Prime Minister VP Singh.

His last stint as an MP was in the Rajya Sabha during 2009-2010.

Following the news of his demise, in a series of tweets, Prime Minister Narendra Modi said that Fernandes was the among the most effective voices for the rights of poor and marginalised.

"A fiery trade union leader, a visionary railways minister and a great defence minister," PM Modi further tweeted. In the early years of his career, Fernandes had joined the socialist trade union movement and became the trade union leader. As the trade union leader, he organised several strikes and bandhs in Bombay in the 1950s and 1960s.

The Prime Minister also recalled his pivotal role in fighting against the Emergency declared by the then Prime Minister Indira Gandhi in the mid 1970s. During the Emergency, he was arrested and tried in the Baroda dynamite case.

Congress president Rahul Gandhi conveyed his condolences to the family and friends of Fernandes.

Congress' chief spokesperson Randeep Surjewala also condoled the demise of the former minister

"My condolences on the passing away of former Union Minister, Sh George Fernandes. May his soul rest in peace," he tweeted.