Kenya's High Court has halted a controversial deal for Indian firm Adani to take over the country's main airport -- a decision hailed by critics on Tuesday as "a win for the Kenyan people".

The Adani Group has been in talks with the government to invest $1.85 billion in Nairobi's Jomo Kenyatta International Airport (JKIA) in exchange for a 30-year lease.

The deal has faced sharp criticism, with many arguing it will lead to job losses for local staff and rob taxpayers of future airport profits.

Freight and passenger fees from JKIA account for more than five percent of Kenya's GDP.

The Law Society of Kenya and the Kenya Human Rights Commission filed a court challenge on Monday saying the deal "violates the principles of good governance, accountability, transparency, and prudent and responsible use of public money."

The High Court approved their request for a delay. The date for a final court decision has yet to be set.

Kenya's government has defended the deal as necessary to refurbish JKIA.

It is one Africa's busiest hubs, handling 8.8 million passengers and 380,000 tonnes of cargo in 2022-23, but is often hit by power outages and leaking roofs.

Adani would add a second runway and upgrade the passenger terminal, according to the Kenya Airport Authority.

Ochiel Dudley, lawyer for the Law Society and Human Rights Commission, told AFP that the delay was a "win for the Kenyan people whose concerns have largely been ignored by a political class eager to push through a seemingly shady deal."

Kenya Aviation Workers Union last month threatened to walk out over the deal but the strike has been pushed back twice to allow for negotiations.