Security agencies say they have uncovered a plot by unnamed terrorists to wreak havoc in the country, especially in areas surrounding the capital, Kampala. Subsequently, Police last week issued a terror alert instructing proprietors of hotels, restaurants and markets to take extra precautionary security measures.

The alert was followed this week by the dramatic arrest of Somalia's junior minister of Defence in Kampala.

Sheikh Yusuf Mohamed Siad, a former Islamist warlord known as Inda'ade, was held while visiting family members in the city. Army Spokesman, Lt. Col. Felix Kulayigye, said the Somali minister had come "for unclear reasons and we took an interest in him".

He also confirmed to The Observer on Wednesday that the Somali minister was linked to the terror threat.

"We are holding him in a residential place. He came in when we were on the watch. We had information that a Somali insurgent was coming," he said.

He however, said that when it became clear who the man was, he was set free. Uganda provides the bulk of troops serving in the African Union Mission to Somalia and for some time now Islamists have targeted these soldiers who are perceived as enemies of Islam.

There have been heightened fears that the Islamists would target Uganda as well. The Observer has seen a letter signed by Lawrence Kibiswa on behalf of the Wandegeya Division Police Commander, warning government ministries and proprietors of bars, restaurants, hotels, lodges, petrol stations, markets, education institutions and places of worship in Wandegeya of a possible terror attack on their premises.

"The popular areas of attack include but are not limited to popular social areas, entertainment areas, worshipping points, shopping centres, transport terminals (parks), markets and fuel depots and stations," reads the two-page letter dated October 2, 2009.

He told managers of these places to look out for suspicious people, objects and report them to Police. "Treat [this matter] as urgent and important," he wrote.

The Minister of Internal Affairs, Ali Kirunda Kivejinja, confirmed that the terror threat is indeed real, but refused to divulge details. "Once a letter is issued by security, it means it (the terror threat) is real. But I cannot tell you the nature of the threat because security matters are not handled like that," Kivejinja said.

Perhaps for security reasons, the letter does not point out the anticipated nature of the threat, why wandegeya is a target, neither does it state who the terrorists are. Wandegeya is famous for its lively night life driven by a string of bars and eating places, as well as proximity to Makerere University.

Abbas Byakagaba, the Director of the Police's Counter-terrorism Agency, told The Observer that he was not aware of this particular threat and had not yet seen the letter in question.

But he added that Police have recently intensified anti-terrorism sensitisation campaigns in some parts of Kampala, teaching people what to do in case of a terror attack.

"We want people to be able to defend themselves in case of an attack and to know how to evacuate safely," he told The Observer this week.

Not new

This is not the first time Uganda is raising a terror alert. In January this year, we reported that the Kampala-based staff of the United Nations Development Programme (UNDP) had been relocated from their headquarters and spread out to various locations to minimise the impact of a possible terror attack.

This followed intelligence reports at the time that some extremists opposed to Uganda's peacekeeping mission in Somalia planned terror attacks in the country. The extremist group was identified as Al Shabaab, a militant Somali group reportedly with links to Al-Qaeda.

However, critics have previously accused the government of using the threat of terror to hunt down opposition supporters. After the recent riots in Buganda, the government controversially preferred terrorism charges against some of the suspected rioters, who allegedly burnt a Police station in Nateete.

Last week, this newspaper reported that President Museveni had ordered the deployment of plain clothed security personnel in areas near Kampala for fear of a possible attack by a shadowy rebel outfit called the Popular Patriotic Front (PPF).

Somalia minister

Somali government officials and Mr. Siad's relatives had earlier said they believed he had been kidnapped by unknown gunmen, but the Somali ambassador in Kampala later confirmed to Reuters that he was aware the minister was in Ugandan custody.

"We want to know what happened, but it seems to have something to do with legal papers," Siid Ahmed said. According to the Somali ambassador to Uganda, the visit was unofficial.

Islamist past

Mr. Siad was previously a member of Hizbul-Islam - an Islamist group that has been fighting the Somali government, which is itself supported by Ugandan peacekeeping troops attached to the African Union force in Somalia. But earlier this year, he defected to the Somali government and was appointed to the defence portfolio.

Uganda has been losing soldiers to attacks by Islamists in recent months. For a senior Somali official with a recent Islamist past to arrive, apparently unannounced, in Kampala, may have raised all sorts of questions in the minds of Ugandan security officials, BBC's Africa editor said.

Somalia has experienced almost constant conflict since the collapse of its central government in 1991. It was hoped the election of moderate Islamist Sheikh Sharif Sheikh Ahmad as president in January and the departure of Ethiopian troops would stop the violence, but Islamist insurgents have kept up their attacks and now control most of Somalia.

Mr. Siad, who became Minister of state for Defence in June, served as head of security under Mr. Ahmad when he briefly governed Somalia as chairman of the Union of Islamic Courts in 2006.