Smallholder farmers make up 70 percent of the east African country's agricultural sector and rely on the informal sharing of seeds when they are in short supply.

But some fear that rules introduced in 2012 and 2016 have made the practice illegal by forcing farmers to only buy and exchange certified seeds.

The government says the law is necessary to maintain quality and productivity, and has imposed penalties of up to two years in prison or a 1 million shilling ($10,000) fine.

A group of 15 smallholders backed by rights groups including Greenpeace are challenging the law in court, saying it favours large corporations at their expense.

The first hearing of the case was held in Machakos in eastern Kenya and petitioners were given until May 26 to submit all documents.

The court is due to deliver a verdict on November 27.

The claimants argue the law undermines food security in a country where more than 2.2 million people face acute hunger, according to the latest Integrated Food Security Phase Classification report.

They also want to protect indigenous seeds that are tied to local traditions and cultures.

But George Bigirwa, director of the Centre of Excellence for Seed Systems in Africa, told AFP the law is not about limiting access to traditional seeds, but about countering a flood of counterfeits.

"If you are going to package and put it on the market for sale it must meet certain standards, that is what the government is saying" Bigirwa said.