The Aam Aadmi Party on Tuesday claimed that Punjab Congress president Navjot Singh Sidhu quit from his post as he 'could not bear" that a Dalit has been made the chief minister of the state.

Sidhu on Tuesday resigned as the chief of the Punjab Pradesh Congress Committee ahead of the Assembly elections in the state early next year.

In a letter to Congress president Sonia Gandhi, Sidhu, however, said he will continue to serve the party. He had taken over as the state party chief in July this year.

"This shows that Navjot Singh Sidhu is against Dalits. One poor son was made the chief minister... this, Sidhu could not bear. It is very sad," AAP spokesperson Saurabh Bhardwaj told reporters.

The AAP is the main opposition in Punjab.

In his letter to Sonia Gandhi, Sidhu wrote, "The collapse of a man's character stems from the compromise corner, I can never compromise on Punjab's future and the agenda for the welfare of Punjab," he wrote in the letter.

"Therefore, I hereby resign as the president of the Punjab Pradesh Congress Committee. Will continue to serve the Congress," he further wrote.

It is immediately not known what prompted Sidhu to leave the post of the Punjab Congress chief.