Stating that he was deeply pained by the decision of his son Anil to join the BJP, Veteran leader A K Antony on Thursday said he would continue to be a Congress worker till his last breath, and castigated the saffron party for taking the country towards a disaster.

The former Kerala Chief Minister also declared his unconditional loyalty to the 'Nehru family' in the face of his son's decision to join the rival party.

Hours after Anil K Antony joined the BJP in the presence of Union ministers Piyush Goyal and V Muraleedharan in New Delhi, his emotionally charged father called it a "wrong" decision.

"I am deeply pained by Anil's decision to join the BJP. It was a wrong decision," Antony told reporters at the KPCC headquarters here.

"I am 82 now. I am at the last stages of my life. I don't know how long I will live and I don't have any interest in having a long life. I will remain a worker of the Indian National Congress as long as I live," the Congress leader said.

The former Defence Minister said he would continue to raise his voice against the "disastrous policies of the BJP and the RSS." Apparently responding to Anil's allegations against the 'Nehru-Gandhi family, Antony said his loyalty would always lie with the Nehru family, which is still at the forefront of the "fearless fight to safeguard the basic ideals of India".

"My loyalty will always be with Nehru family. The members of that family, even in the midst of being hunted (by the BJP), are at the forefront of the fearless fight to safeguard the values of the Indian constitution," Antony said.

He said that during the freedom struggle and after Independence, the Nehru family treated every Indian as one, irrespective of their caste, religion, language, and region.

Anil, who headed the Digital Media cell of the Kerala Pradesh Congress Committee, quit the Congress two months ago, after criticising the party's stand on the controversial documentary film of the BBC on Prime Minister Narendra Modi, and slammed the Congress leadership for working for a "single family" instead of the country.

Antony accused the BJP of destroying the constitutional values of the country. "Unity in diversity is the Indian concept. That is the real vision of India's unity. But the BJP believes only in uniformity. India's unity, people's unity, social harmony, everything is demolished," the Congress veteran said, blaming the BJP He also alleged that the Narendra Modi-led government, since 2014, had been "systematically diluting diversity and secularism" which are the "cornerstones" of India's unity.

Antony concluded by saying that he would no longer comment on or discuss Anil's decision to join the BJP. "This is my first and last reaction on this matter," he said.

Meanwhile, the Kerala Pradesh Congress Committee (KPCC) came down heavily on Anil for joining the BJP, accusing him of "betraying" his father and veteran party leader Antony on "Maundy Thursday".

KPCC chief K Sudhakaran said Anil had not been given any party responsibilities and that his joining the BJP was not a matter of concern for the Congress.

He also asked Anil to "examine the plight" of those who left Congress and joined the BJP in the past. "No one who sweats for the party will leave Congress,"Sudhakaran said.

"Today (Maundy Thursday) is the day of Judas (Iscariot) who betrayed Jesus Christ for a payment of 30 silver coins. Many such things will happen on that day. This (Anil joining BJP) should also be seen as such an incident," Sudhakaran told reporters in Thrissur.

Reacting sharply, the KPCC chief said it was Anil's "present to his father" on Maundy Thursday.

According to the Bible, one of Christ's twelve disciples, Judas Iscariot, made an agreement with the authorities to betray Jesus in exchange for 30 pieces of silver, on a Wednesday, which came to be known as Holy Wednesday.

On the next day, which came to be known as Maundy Thursday, signifying the Last Supper of Christ, when Jesus joined his disciples after a prayer, Judas kissed him on the cheek to help authorities identify him. Following Judas's betrayal, they took Jesus away and later crucified him on a Friday, which came to be known as Good Friday among Christians.

Leader of Opposition in the state Assembly, V D Satheesan, said Anil was falling into the trap of the BJP and nothing would happen to the Congress because he joined the saffron party. He said Anil would realise its danger later.

"Anil has not rendered any services directly or indirectly to the Congress or the allied organisations. Anil did not even perform the assigned tasks properly, he said.

He also said this was the contempt Anil showed as a son to his father.

Antony's political integrity or idealistic courage will not be harmed because his son has joined the BJP, he said.

Senior Congress leader Ramesh Chennithala said Anil's decision to join the BJP was immature.

Meanwhile, there has been no reaction from Senior Congress leader Shashi Tharoor on the development. Anil was said to be close to Tharoor, who represents Kerala's Thiruvananthapuram seat in the Lok Sabha.

Tharoor had earlier rejected Anil's views on the BBC documentary on Gujarat riots and termed as "immature" his argument that it was an infringement on India's sovereignty.

He had said Anil, who had handled the digital communications of the grand old party in the State for sometime, was a "good person" and that he had not discussed the BBC documentary issue with him.

In his resignation letter sent to the Congress leadership two months ago, Anil had especially thanked Tharoor for his support.

Kerala's ruling CPI(M) alleged that there were no boundaries that prevented Congressmen from joining the BJP. CPI(M) state secretary M V Govindan said it was easy to switch parties because the political positions of both parties were the same.

Sensing danger in Anil joining the BJP, the CPI(M) leader said it was part of the saffron party's effort to bring minorities closer to them.