A top opponent of Indian Prime Minister Narendra Modi said he would return to jail Sunday, the end of the bail term issued to allow him to campaign in just-concluded national elections.

Arvind Kejriwal, chief minister of the capital Delhi and a key leader in an opposition alliance formed to compete against Modi in the polls, was detained in March over a long-running corruption probe.

He is among several leaders of the bloc under criminal investigation, with colleagues describing his arrest the month before general elections began as a "political conspiracy" orchestrated by the ruling Bharatiya Janata Party (BJP).

India's top court granted him bail last month, giving a fleeting boost to the opposition's quixotic campaign to oust Modi, but ordered him at the same time to return to custody once voting in the six-week poll concluded.

He will hand himself into Delhi's Tihar prison on Sunday afternoon, he said.

"I came out for election campaign for 21 days... today I will surrender by going to Tihar," he wrote on social media.

However, he said he would first visit a memorial to Mahatma Gandhi, pray at a Hindu temple and visit his party office to "meet all the workers and party leaders".

"All of you take care of yourselves," he added. "I will take care of you all in jail. If you are happy, then your Kejriwal will also be happy in jail."

Kejriwal's government was accused of corruption when it implemented a policy to liberalise the sale of liquor in 2021 and give up a lucrative government stake in the sector.

The policy was withdrawn the following year, but the resulting probe into the alleged corrupt allocation of licences has since led to the jailing of two top Kejriwal allies.

Hindu-nationalist Prime Minister Narendra Modi looks set to win a third straight landslide election victory after voting ended on Saturday.

Exit polls showed he was well on track to triumph and Modi himself was certain he had prevailed, saying he was confident that "the people of India have voted in record numbers" to re-elect his government.

Results will be formally announced on Tuesday.