Mr Robow, The Independent understands, was rescued from al-Shabaab territory by US special forces in a mission with British help.

A western security official who was involved in the operation said: “His seniority and the standing of Robow in the community means that his defection was a big blow to al-Shabaab.

“Now what has happened to him will raise doubts among others who may want to come over. There are questions which need to be asked about who really gains from all of this.”

The UK, Germany and the European Union, it has been reported, have suspended financial aid to the police force from the Baidoa region for the time being. Mr Haysom wrote to the minister of internal security, urging that “appropriate action is taken to hold any perpetrators, including commanding officers, responsible”.

The UN Security Council adopted a British drafted proposal expressing “regret” at the expulsion of Mr Haysom, a South African lawyer and diplomat who was legal adviser to Nelson Mandela, and the expectation of “full cooperation between Somalia and the United Nations”.

The Somali government, however, has told UN secretary-general Antonio Guterres that it will not accept Mr Haysom’s return.

The UK’s decision to condemn the UN envoy’s expulsion and cancellation of the defence secretary’s visit have, so far, drawn a muted reaction from the Somali government. A Somali website published a report which claimed that “sources” inside the Somali president and prime minister’s offices had “confirmed” that “explosives from the UK government” were used in a bombing in which 30 people were killed and that tail fins of mortar rounds showed they were “UK military”.

Somali government officials said that there was no evidence to back any of the allegations and wanted to stress that none of them had emanated from the office of the president or the prime minister. One official said that “it is unfortunate” that “such material is being put out so irresponsibly”.

But what happened to Mokhtar Robow, now in the intelligence service’s prison, provides a glimpse of the bitter divisions in this fractured society after decades of conflict, and the problems faced by the international community when dealing with a country beset by terrorism, poverty and economic collapse.

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