U.S. warns of attack threat in Kenyan port city NAIROBI (Reuters) - The U.S. embassy in Kenya has warned of an imminent threat of an attack on the Kenyan port city of Mombasa and asked all its government workers to leave the coastal town, which has been hit by a series of attacks. The embassy said in a statement dated June 22 on its website that it had also suspended travel for its government officials to Mombasa, a tourist destination popular with foreigners, until July 1. Mombasa, the capital Nairobi and other parts of Kenya have suffered a series of grenade attacks since Kenya sent troops into Somalia last year to pursue al Qaeda-allied al Shabaab insurgents it blames for a surge in violence and kidnappings threatening tourism in east Africa's biggest economy. "This is to alert all U.S. citizens in Kenya, or planning to travel to Kenya in the near future, that the U.S. Embassy in Nairobi has received information of an imminent threat of a terrorist attack in Mombasa," the embassy statement said. All U.S. government travel to Mombasa is suspended until July 1, 2012. All U.S. government personnel are required to leave Mombasa. The embassy said private citizens would not face the same restrictions, but advised them to heed the warning while planning their travels. The warning comes days after police arrested two Iranians after seizing chemicals they suspected were going to be used to make explosives in Mombasa. In the most recent attack in the country, a bomb exploded in a trading centre in the heart of Nairobi in late May, wounding more than 30 people. One person later died from their injuries. Gunmen also detonated grenades outside a nightclub in Mombasa in May, killing one person and wounding several others. The embassy has issued four emergency messages warning of potential attacks in the country since October, when Kenya sent its troops to Somalia. Reporting by George Obulutsa; Editing by Alison Williams