In jail, P Chidambaram has not stopped his social media activity.

Highlights P Chidambaram took swipes at PM Modi over his birthday wishes for him

As you have wished, I want to continue to serve the people: P Chidambaram

"Your investigating agencies have prevented me from doing so," he charged

Congress leader P Chidambaram, who is in Delhi's Tihar jail in connection with a corruption case, tweeted today that he had received Prime Minister Narendra Modi's birthday wishes mailed to his village in Tamil Nadu and redirected to him in prison.

In a tweet sharing a screenshot of the letter in Tamil dated September 16, Mr Chidambaram said he was "pleasantly surprised to receive your greetings on my birthday."

The Congress leader went on to take swipes at the Prime Minister.

"As you have wished, I want to continue to serve the people. Unfortunately, your investigating agencies have prevented me from doing so," Mr Chidambaram tweeted.

"Once the harassment ends, I shall be back among the people that both you and I are committed to serve," he posted in another tweet.

P Chidambaram is in judicial custody in the INX media case.

Mr Chidambaram spent his 74th birthday in jail; the former union minister was sent to Tihar, Asia's largest prison, on September 5, in the INX Media case.

He is accused of signing off on a huge infusion of foreign funds into the company INX Media in 2007, when he was the country's Finance Minister. His son Karti Chidambaram is accused of receiving kickbacks for facilitating the process. The two were named by INX co-founder Indrani Mukerjea, who is currently in jail in Mumbai for the murder of her daughter.

In jail, Mr Chidambaram has not stopped his social media activity. He has kept his timeline on Twitter updated by posting through his family.

Soon after the "Howdy, Modi!" event in Houston, which featured a joint appearance by PM Modi and US President Donald Trump, Mr Chidambaram mocked a statement the Prime Minister had made in his address to the Indian American community -- "If you ask me Howdy, Modi, I'll say - Bharat mein sab achha hai (everything is great in India)."

Seizing the comment, Mr Chidambaram retorted: "Bharat mai sab achha hai. Except for unemployment, loss of existing jobs, lower wages, mob violence, lockdown in Kashmir and throwing Opposition leaders in prison."