Former Jharkhand chief minister Champai Soren joined the Bharatiya Janata Party on Friday, two days after he resigned from the Jharkhand Mukti Morcha citing dissatisfaction with the party's current style of functioning and facing 'bitter humiliation'.

The joining of the 67-year-old leader to the BJP is seen as a significant boost for the party's efforts to strengthen its connection with the Scheduled Tribes, a strong support base of the JMM.

The veteran politician, who was known to be close to JMM chief Shibu Soren, was visibly emotional after he was welcomed into the saffron fold.

"After I was put under surveillance by the Jharkhand government in Delhi and Kolkata, my resolve to join BJP strengthened," he said.

Responding to the development, the JMM claimed that despite its ploy, BJP will not succeed in its mission and the next government in Jharkhand will be formed under the leadership of Hemant Soren, the current CM.

Soren, along with his son Babulal, crossed over to the saffron party at a ceremony attended by Union Minister Shivraj Singh Chouhan, Assam Chief Minister Himanta Biswa Sarma, senior leaders Laxmikant Bajpai, Arjun Munda and BJP state president Babulal Marandi in Ranchi.

The BJP can save the tribals' identity and check infiltration in Jharkhand's Santhal Pargana, Soren said adding that atrocities were committed on tribals during the erstwhile Congress government's regime at the Centre.

Alleging that the tribal identity was put 'at stake' by the Congress, Soren said, "I am committed to delivering justice to the people."

"I nurtured JMM with my sweat and blood but was humiliated and insulted. I am compelled to join the BJP. I am now proud to be a member of the world's largest political party. I was not in a position to tolerate humiliation and snooping," he said.

Soren said he will work as a committed member of the saffron party and would not retire from politics as 'I was embarrassed, and that's why I had decided to retire (from politics). However, because of the love and support of the people of Jharkhand, I decided not to retire from politics'.

Assam Chief Minister Himanta Biswa Sarma accused the 'corrupt' JMM-led coalition of keeping Chamai Soren under surveillance for the last six months and said a befitting reply awaits the coalition in two months referring to the assembly elections due in the state later this year.

Sarma is also the BJP co-in charge for assembly elections in Jharkhand.

Union Agriculture Minister Chouhan took a jibe at JMM, saying 'Tiger abhi zinda hai' (Tiger is still alive), apparently referring to the alleged humiliation of Soren and his parting ways with JMM to embrace BJP.

Soren is popularly known as the 'Kolhan Tiger'.

"Champai Soren had fought a very tough battle for the creation of Jharkhand and it was due to his efforts that former Prime Minister Atal Bihari Vajpayee created the state," Chouhan said.

Sita Soren, sister-in-law of Hemant Soren who joined the BJP before Lok Sabha polls quitting JMM, accused the ruling party of 'snatching the bow and arrow' which belonged to her late husband Durga Soren and using it to frighten people.

A set of a bow and an arrow is the poll symbol of the JMM.

Sita Soren in March had joined the BJP accusing JMM of isolating and neglecting her and her family after her husband Durga Soren's demise.

Champai Soren was appointed chief minister on February 2, following Hemant Soren's resignation and subsequent arrest by the Enforcement Directorate in a money laundering case.

He left the post on July 3, clearing the way for Hemant Soren to resume office on July 4 after being granted bail.

In a letter to party supremo Shibu Soren on Wednesday, Champai said he was compelled to quit after being 'aggrieved by the present style of functioning of the JMM and its policies'.

'I have never imagined that I would quit JMM, a party which is like a family to me... The turn of events of the past forced me to make this decision with much pain...I am pained to say that the party has deviated from its principle,' he said in the letter.

Champai had previously met Union Home Minister Amit Shah in New Delhi to announce his decision to join the BJP.

On Tuesday, Champai had asserted that he would be switching sides to save tribal identity and existence, which is 'at stake in the state's Santhal Pargana due to 'rampant' infiltration from Bangladesh'.

These intruders are causing economic and social harm to the local people, and if they are not stopped, the existence of 'our society in Santhal Pargana will be in danger', he had claimed.