Police said Friday they had arrested three people in connection with alleged extortion letters sent to Indian cricket captain Mahendra Singh Dhoni [Images].

Security was beefed up outside Dhoni's family home in Ranchi after a man claiming to be an associate of Dawood Ibrahim [Images], the country's most wanted gangster, demanded Rs 50 lakh from the cricket star in a letter on Monday.

A second letter sent two days later threatened to blow up the house if police were asked for help. Police sent 45 commandos to keep watch.

Dhoni arrived in his hometown Ranchi in Jharkhand on Tuesday, but has since left for Mumbai [Images].

"Three people have been arrested in connection with the extortion and threat letters written to Indian cricket captain Mahendra Singh Dhoni," a state police official said.

"We have interrogated more than seven people in connection with two letters."

Ibrahim is accused of masterminding the country's most deadly bombings in 1993, which killed at least 250 people in Mumbai. He has eluded authorities for the past 15 years and is believed to be hiding in Pakistan.

Dhoni had already received extra security cover after Maoist rebels made death threats against him in 2007, police said.

But he was unhappy with the arrangements and applied for government permission for his security team to carry more sophisticated weapons.