Qatar has asked Kenya to lease it 40,000 hectares of land to grow crops as part of a proposed package that would also see the Gulf state fund a new £2.4bn port on the popular tourist island of Lamu off the east African country.

The deal is the latest example of wealthy countries and companies trying to secure food supplies from the developing world.

Other Gulf states, including Saudi Arabia and the United Arab Emirates, have also been negotiating leases of large tracts of farmland in countries such as Sudan and Senegal since the global food shortages and price rises earlier this year.

The Kenyan president, Mwai Kibaki, returned from a visit to Qatar on Monday. His spokesman said the request for land in the Tana river delta, south of Lamu, in north-east Kenya was being seriously considered.

"Nothing comes for free," said Isaiah Kabira. "If you want people to invest in your country then you have to make concessions."

But the deal is likely to cause concern in Kenya where fertile land is unequally distributed. Several prominent political families own huge tracts of farmland, while millions of people live in densely packed slums.

The country is also experiencing a food crisis, with the government forced to introduce subsidies and price controls on maize this week after poor production and planning caused the price of the staple "ugali" flour to double in less than a year.

Kibaki said that Qatari Emir Sheikh Hamad bin Khalifa al-Thani was keen to invest in a second port to complement Mombasa, which serves as a gateway for goods bound for Uganda and Rwanda and is struggling to cope with the large volumes of cargo.

By building docks in Lamu, Kenya hopes to open a new trade corridor that will give landlocked Ethiopia and the autonomous region of Southern Sudan access to the Indian Ocean. Kabira said that if the financing was agreed, construction of the port would begin in 2010.

Qatar, which has large oil and gas revenues, imports most of its food, as most of its land is barren desert and just 1% is suitable for arable farming. It has already reportedly struck deals this year to grow rice in Cambodia, maize and wheat in Sudan and vegetables in Vietnam.

Much of the produce will be exported to the Gulf. Qatar's foreign ministry in Doha did not return calls today, but Kabira said that its intention was to grow "vegetables and fruit" in Kenya.

The area proposed for the farming project is near the Tana river delta where the Kenyan government owns nearly 500,000 hectares (1.3m acres) of uncultivated land.

But a separate agreement to allow a local company to grow sugarcane and build a factory in the area has attracted fierce opposition from environmentalists who say a pristine ecosystem of mangrove swamps, savannah and forests will be destroyed.

Pastoralists, who regard the land as communal and rear up to 60,000 cattle to graze in the delta each dry season, are also opposed to the plan.

"We will have to ensure that this new project is properly explained to the people before it can go ahead," said Kabira.

The sudden rush by foreign governments and companies to secure food supplies in Africa has some experts worried. Jacques Diouf, director general of the UN's food and agricultural organisation (FAO), recently spoke of the risk of a "neo-colonial" agricultural system emerging.

The FAO said some of the first overseas projects by Gulf companies in Sudan, where more than 5 million people receive international food aid, showed limited local benefits, with much of the specialist labour and farming inputs imported.

A deal struck last month by Daewoo Logistics and Madagascar to grow crops on 1.3m hectares of land also attracted strong criticism. While the South Korean firm has promised to provide local jobs and will have to invest in building roads and farming infrastructure, it is paying no upfront fee and has a 99-year lease.