Navjot Singh Sidhu on Tuesday resigned as the chief of the Punjab Pradesh Congress Committee.

In a letter to Congress president Sonia Gandhi, Sidhu, however, said he will continue to serve the party.

Sidhu had taken over as the state party chief in July this year.

"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.

Sidhu not stable, not fit for Punjab: Amarinder Singh

Soon after the resignation of Navjot Singh Sidhu as the Punjab Congress president, former chief minister Amarinder Singh on Tuesday dubbed the cricketer-turned-politician as a man who is "not stable" and "not fit" for the border state.

"I told you so...he is not a stable man and not fit for the border state of punjab," Singh tweeted.

Sidhu resigned as the PCC chief and sent his resignation to Congress president Sonia Gandhi on Tuesday.

Singh has been vehemently opposing Sidhu and has alleged that he has links with Pakistan. The former chief minister has openly challenged Sidhu, saying he will oppose him tooth and nail.

Sidhu was instrumental in the ouster of Singh, who quit as chief minister earlier.