It was billed as a UK-US drug summit, but British officials claim it didn't turn out quite that way. A three-day visit to London by General Barry McCaffrey, the US "drug tsar", provoked embarrassment and tension in equal doses.

According to UK officials, the visit to London as part of a European tour that ended yesterday in Paris appears to have been arranged by Gen McCaffrey with one eye firmly based on a pre-election US audience.

In 1996, he was chosen by President Bill Clinton as director of the White House Office of National Drug Control Policy. To Republicans, Gen McCaffrey hasn't been tough enough on drugs, while "legalisers" have argued that the US continues to ignore the underlying social causes of addiction by putting too much emphasis on law enforcement.

His European agenda was arranged in an effort to show that this Vietnam and Gulf War veteran-turned-social-policy-crusader could be all things to all men.

Yet many British observers were struck more by his military demeanour and that of some of his entourage. In a press briefing at a US embassy residence last Sunday, Gen McCaffrey tried to eschew such military metaphors as "war on drugs", instead describing drug abuse by one in 17 Americans as a "cancer".

When questioned he used less diplomatic language, confirming his belief in the need for more military assistance to Colombia where "vital US interests are at stake", and implying European governments needed to do more in fighting drugs. Gen McCaffrey presented officials charts claiming that the Colombians were increasingly redirecting their cocaine from the US and towards Europe. The rest of his time in London was taken up with hastily rearranged schedules partly due to threats of demonstrations by "legalisers" and partly the absence of government ministers.

Some British officials found themselves trying to smooth over the results of the heavy-handed tactics sometimes adopted by the McCaffrey entourage.

On Monday, a visit to Goldsmith's College to mark the inauguration of a new drug information web site had the McCaffrey bandwagon unsettled by a student demonstration and by the statement of a leading academic expert on drug prevention who told him that UK schools had nothing to learn from an educational programme Britain had imported from the US. "Our research shows that it simply is not working here," said Louise O'Connor, head of the drugs research unit at Roehampton University.

The following day, British and US officials issued a joint statement that both sides had "exchanged views and experiences on a wide range of drug policy issues" at a press conference where tension simmered. While the official spin was on co-operation, the trip served to underline the differences in personalities and the policies involved in both countries.

The government has borrowed the term "drug tsar" from the US to boost the profile of Keith Hellawell, the former senior policeman given the job of national drugs co-ordinator. He has tried recently to redefine himself in the public eye as a conciliator between government departments.

Unlike his US counterpart, the UK drugs co-ordinator has no ministerial status or obvious executive powers. But in an interview on the eve of the McCaffrey visit, Mr Hellawell argued that this put him at an advantage compared to the general.

"I have a direct line to those involved in drugs programmes on the ground. My job is to co-ordinate between ministries, not to fight for my own budget. I'm not seen as a threat by other ministers," he said conscious of Gen McCaffrey's struggles in dealing with other departments of state and Congress.