NEW DELHI, Sept. 27 (Xinhua) -- India's main ruling Bharatiya Janata Party (BJP) lost its oldest alliance partner -- the Shiromani Akali Dal (SAD) after it announced its withdrawal from the country's ruling National Democratic Alliance (NDA) as a mark of protest against the recent farm bills passed in the parliament, a senior SAD leader confirmed on Sunday.

SAD president Sukhbir Singh Badal reportedly told media that the farm bills passed by the Indian parliament were detrimental to the farmers' interests.

Badal's wife Harsimrat Kaur Badal had resigned from the federal cabinet earlier this month. She had held the portfolio of minister of food processing industries.

Tens of thousands of farmers had been protesting in several Indian states, particularly in north India, over the past few days against the federal government's recently passed farm bills.

The SAD is a key political party in the country's northern state of Punjab. It had been in the BJP-led NDA for over 22 years.

Currently the NDA comprises of nearly 30 political parties. Besides the BJP, all others are small state-level political parties.

Late last year, the Shiv Sena, a major political party in southwestern state of Maharashtra, moved away from the alliance citing political differences with the BJP.

Despite the SAD's withdrawal from the NDA, the alliance government headed by Prime Minister Narendra Modi enjoys the support of more than 330 lawmakers in lower house of parliament -- the Lok Sabha out of the total strength of 543.

The BJP alone has over 300 lawmakers in the house.