NEW DELHI (Reuters) - An Indian court on Friday suspended a lower court's order granting bail to opposition leader and Delhi Chief Minister Arvind Kejriwal in a graft case, extending his pre-trial detention at least until next week.

Kejriwal is a fierce critic of Prime Minister Narendra Modi and a former anti-corruption crusader whose decade-old Aam Aadmi Party (AAP) quickly rose to mainstream politics, although its clout is relatively small compared to older opposition parties.

He was arrested by India's financial crime-fighting agency in March, weeks before national elections, on corruption allegations relating to Delhi's liquor policy and was granted bail by a city court on Thursday.

Kejriwal has denied the allegations and termed them politically motivated.

The agency challenged the bail order in the Delhi High Court on Friday morning, arguing that the lower court had not considered documents it submitted and had not given it adequate opportunity to oppose the bail.

Reserving the order for "two to three days", the High Court said on Friday evening: "Till pronouncement, the operation of the impugned order shall remain stayed (suspended)."

Last month, India's top court granted Kejriwal three weeks' temporary bail to campaign in the elections, which concluded earlier this month, and he returned to prison on June 2.

Kejriwal's AAP is a member of the opposition 'INDIA' alliance, which defied predictions to deny an outright majority to Modi's Bharatiya Janata Party (BJP) in the general election, forcing the prime minister to form his first coalition government with support from fickle regional allies.

However, the AAP itself failed to make any significant gains in Delhi and the northern state of Punjab, where it also forms the government.

(Reporting by Sakshi Dayal, Shivam Patel and Shilpa Jamkhandikar; editing by Sudipto Ganguly and Mark Heinrich)

By Sakshi Dayal and Shivam Patel