African nations must stand up for themselves when confronted by Western countries wanting to exploit their raw materials, the Iranian president said on Wednesday during a visit to Kenya.

Mahmoud Ahmadinejad was mobbed by thousands of Shia Muslims chanting "Allah u Akbar" (God is great), as he arrived to give a speech in a field in the sweltering port of Mombasa.

"Western countries have for years oppressed African states, exploited Africa's natural resources," he said.

Iran is a leading importer of Kenyan tea and is helping with several major projects aimed at upgrading the energy sector and infrastructure of east Africa's biggest economy.

Kenya is a key ally in the United States' "war on terror".

But that has not dampened its relations with Iran, which Ahmadinejad told the crowd had now become closer than ever.

Ahmadinejad arrived in Kenya late on Tuesday and signed bilateral agreements with Kenyan President Mwai Kibaki on water supply, oil and direct flights between the two countries.

On Wednesday, the Iranian leader flew to Mombasa and was due to leave later for Djibouti, en route to Comoros. In Mombasa, many men struggled with security guards to try to touch him.

"Can you imagine? The President of Iran greeted me! God is surely coming down to earth," said one boy, 13-year-old Suleiman, grinning as he pushed his bicycle home after following the Iranian delegation to Kenya's historical Fort Jesus site.

Another teenager fought with security, shouting: "This is a once-in-a-lifetime opportunity, you cannot stop me." Many were stunned when the diminutive leader kissed the feet of an elder.

"So humble," whispered one local woman in admiration.