Kenya's high court has temporarily blocked a proposed deal for India's Adani Group to lease the country's main airport for 30 years in exchange for expanding it, court documents showed.

In a joint application, the Law Society of Kenya (LSK), the country's main bar association, and the Kenya Human Rights Commission (KHRC) told the court on Monday that the country could independently raise the $1.85 billion required to upgrade the airport in the capital Nairobi.

LSK and KHRC said the alleged 30-year lease of Jomo Kenyatta International Airport (JKIA), East Africa's largest aviation hub, was unaffordable, threatened job losses, was a fiscal risk and did not offer taxpayers value for money, court documents published by the KHRC on their website showed.

The high court granted the request for leave to file a judicial review to challenge the possible lease of JKIA to Adani, LSK President Faith Odhiambo wrote on the social media platform X late on Monday.

"The court has meanwhile issued a stay prohibiting any person from implementing or acting on the privately initiated Adani proposal over JKIA pending the conclusion of the court case," Odhiambo said.

The Adani Group did not immediately respond to a Reuters request for comment. A spokesperson for the Kenya Airports Authority told Reuters: "We are not going to comment on matters in court."

Last month, the Kenya Aviation Workers Union called for a strike over the proposed deal, saying that it would lead to job losses and bring in non-Kenyan workers.

Kenya's government has said the airport is operating above capacity and needs modernising but that it is not for sale and that no decision has been made on whether to proceed with what it calls a proposed public-private partnership to upgrade the site.

It said in July that Adani's offer was being reviewed. If a deal is agreed, the government said there would be safeguards to ensure Kenya's national interests are protected.