Corruption in Kenya is increasing Britain's exposure to drug trafficking and terrorism
The East African nation's "porous" borders meant groups such as al-Qaeda see it as being "wide open", he added.
Kenya was also being targeted by drug cartels, bringing in heroin and cocaine which ended up in Britain, Mr Howells said during an official visit.
Kenyan ministers deny that corruption is making the country a "soft touch".
Mr Howells, who visited the capital Nairobi and the port of Mombasa, said: "People can be bought, right from the person who works at the docks in Mombasa up to the government."
He added: "This weakness has been recognised by drug-traffickers and probably by terrorists too."
Several drug seizures in the UK this year have come via Kenya.
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