KAMPALA (Reuters) - The United States has received intelligence of a "specific terrorist threat" against churches and other places of worship in the Ugandan capital, its embassy there said.

A security message on the embassy's website did not say who was planning the attack, but Somali Islamist militants have previously threatened, and struck, Uganda and other east African countries that have sent troops into Somalia.

"The threat information indicates a group of attackers may be preparing to strike places of worship in Kampala, particularly churches, including some that may be frequented by expatriates, in May or June," said the notice dated May 6.

Regional economies have been on a heightened state of alert since militants killed at least 67 people, including children, when they rampaged through an upscale Kenyan shopping mall in September. Somalia's al Qaeda-linked al Shabaab group claimed responsibility.

Kenya has also suffered a string of gun and bomb attacks, most recently over the weekend in Nairobi and the port city of Mombasa. The government blamed them on al Shabaab and its sympathisers.

In 2010, al Shabaab bombers killed 77 people watching the World Cup soccer final in a bar and restaurant in Kampala. In March, the Ugandan authorities warned of a militant plot to strike petrol tankers and fuel depots.

Kenya, Uganda, Ethiopia and Burundi as well as Djibouti and Sierra Leone have all sent troops into Somalia to crush al Shabaab.

The group, bent on imposing its version of Islamic law across Somalia, has turned increasingly to al Qaeda-inspired suicide attacks as a military offensive weakens it as a conventional fighting force.