African troops plan to launch an attack on a Somali Islamist base in the port of Kismayu next month in an attempt to hasten an end to the insurgency that has troubled the region for more than 20 years, says Raila Odinga, Kenya’s prime minister.

The offensive would have started this month, Mr Odinga said in an interview with the Financial Times. However, commanders of the the African Union peacekeeping force, which will be involved in the attack alongside Kenyan troops, delayed the plan for reasons that are unclear.

Kenya invaded Somalia last year after a series of kidnappings and killings, carried out by Somali al-Shabaab militants, which threatened the lucrative tourism industry.

Simultaneous offensives by Ethiopian and AU forces have been successful in driving al-Shabaab from Mogadishu and other parts of Somalia.

But the port of Kismayu remains under the militants’ control.

“Our troops are ready to move. It’s going to happen because unless we capture Kismayu we cannot say we have hurt al-Shabaab. It’s their main supply base,” said Mr Odinga. “They are weakened already, but as usual, a besieged enemy is like a wounded buffalo. It is more dangerous.”

Kenya which borders Somalia, has absorbed up to a million refugees from its war-torn neighbour in a tide that Mr Odinga said had severe economic and security repercussions for east Africa’s biggest economy.

Last week, a grenade attack in Nairobi killed one person – the latest in a series of assaults blamed by the Kenyan authorities on Somali Islamist militants linked to al-Qaeda.

Mr Odinga is leading opinion polls in advance of presidential elections due next March, when his historic rival and coalition partner Mwai Kibaki stands down as president. Should Mr Odinga win, he said he would ensure that Kenya played a leading role in reinforcing regional stability and encouraging economic integration.

“We will work to bring this region together. There are a lot of common problems and common interests.”

In the past week, Sudan and South Sudan have agreed on a formula for sharing oil revenues, in the first breakthrough for months in resolving that long-running conflict.

Mr Odinga said the recent discovery of oil in a part of northern Kenya bordering South Sudan had reinforced the case for a pipeline transporting oil from South Sudan’s capital, Juba, to a putative port on the Kenyan coast at Lamu.

A besieged enemy is like a wounded buffalo. It is more dangerous- Raila Odinga

South Sudan shut down oil production in January after it failed to agree transit fees for oil exported through pipelines in Sudan, from which it seceded last year. The southern government has since been in talks with Kenya and other parties, including Chinese, Malaysian, Japanese and Indian oil companies, about alternative routes for its oil.

Mr Odinga said a pipeline and refinery from South Sudan through Kenya would cost $4bn to $5bn and take about 18 months to build.

No start date has been mooted and there are no committed investors yet.

However, he said: “The dynamics have changed because we have also found oil near the South Sudan border.”

He added that Britain’s Tullow Oil, which announced the Kenyan oil find earlier this year, had expressed optimism to him about the extent of the discovery, which could be larger than that made in neighbouring Uganda in recent years.

The prime minister, who has faced down recent allegations of nepotism and corruption in a tell-all account published by a former aide, is seeking to initiate a string of big projects, including the construction of a new port at Lamu, and railway lines from Douala in Cameroon to link west and east Africa.

The government has also faced criticism over claims that it spent $3,000 apiece on chairs for its newly refurbished parliament. Mr Odinga said the chairs could not have cost that much as they were made in Kenya’s prisons. He said the story had been sensationalised.

The development of regional rail and road networks would bolster intra-African trade and help open up the continent’s isolated interior at a time of rapid economic and demographic expansion.

“We have been talking about intra-African trade, but until now it’s been a pipe dream because of the infrastructure constraints. . . But sub-Saharan Africa has a trillion-dollar economy and that is expected to double in the next 10 years,” he said, adding that Kenya was in prime position to benefit.

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