India captain Mahendra Singh Dhoni backed by Ravichandran Ashwin

India all-rounder Ravichandran Ashwin has defended under-fire skipper Mahendra Singh Dhoni, who says he is willing to step aside as captain following their first one-day series defeat to Bangladesh.

Ashwin said Dhoni was not to blame for India's defeats in the first two matches of the series to Bangladesh, saying "we failed as a group".

India suffered a six-wicket loss to Bangladesh on Sunday in Dhaka, sealing the international series for the hosts.

"He (Dhoni) is a legend of Indian cricket. He has done so much for the nation," Ashwin said at a press conference in Dhaka ahead of the third and final match on Wednesday.

"You can't blame him for the whole team's performance. That's not fair. We have failed as a group. We need to grow up as a group."

Ashwin, Dhoni's team-mate in the Indian Premier League franchise Chennai Super Kings, said the team were fully behind their captain.

"As far as I am concerned it's like an army, if you don't go behind your leader then you are definitely going to get shot," he said. 

Dhoni, who turns 34 next month, has won a string of trophies for India since taking the helm in 2007.

But the defeats in Bangladesh again raised questions about his recent form as captain after India's semi-final exit from the World Cup in Australia and New Zealand earlier this year.

The wicketkeeper-batsman quit the Test captaincy midway through the Australia tour in December and was replaced by batsman Virat Kohli.

"If it is a justifiable thing that if you remove me and Indian cricket will start doing really well, and if I am the reason for all the bad that is happening to Indian cricket, definitely I would love to step away and play as a player," Dhoni said after Sunday's defeat in Dhaka.