LONDON - It's not exactly diplomatic -- details of what British ambassadors really think about their foreign hosts were disclosed Sunday following the release of a series of frank, and sometimes outright rude, letters to London from embassies around the world.

Nigerians are maddening, Nicaraguans often dishonest, Canadians deeply unimpressive and Thai's commonly lewd, British diplomats claim in notes sent to Britain's Foreign Office over the last five decades.

The letters, disclosed to the BBC under Freedom of Information laws, also reveal how diplomats were bored by endless rounds of cocktail parties, and exasperated by the British government's failure to shake off its stuffy image overseas.

Until 2006, ambassadors retiring from their post or moving country traditionally sent a valedictory dispatch to London, offering their candid personal assessment of the country in which they had served.

In a 1967 memo, Roger Pinsent, Britain's outgoing ambassador to Nicaragua, was scathing in his criticism.

"There is, I fear, no question that the average Nicaraguan is one of the most dishonest, unreliable, violent and alcoholic of the Latin Americans," Pinsent wrote.

Two years later, David Hunt -- then high commissioner to Nigeria -- said the West African country's leaders had "a maddening habit of always choosing the course of action which will do the maximum damage to their own interests."

"Africans as a whole are not only not averse to cutting off their nose to spite their face; they regard such an operation as a triumph of cosmetic surgery," Hunt claimed in his letter.

Lord Moran, high commissioner in Ottawa, Canada, between 1981 and 1984, claimed Canadians had limited talents.

"Anyone who is even moderately good at what they do -- in literature, the theatre, skiing or whatever -- tends to become a national figure. And anyone who stands out at all from the crowd tends to be praised to the skies and given the Order of Canada at once," Moran wrote in his letter, according to files released to the BBC.

Anthony Rumbold, Britain's ambassador to Thailand from 1965 to 1967, mocked his hosts for an apparent lack of culture. "They have no literature, no painting and only a very odd kind of music; their sculpture, ceramics and dancing are borrowed from others, and their architecture is monotonous and interior decoration hideous," Rumbold wrote.

"Nobody can deny that gambling and golf are the chief pleasures of the rich, and that licentiousness is the main pleasure of them all," he said.

Other diplomats used their letters to criticize British bureaucracy, and the sometimes dull world of international relations.

"One of the great failures of the diplomatic service has been its inability to cast off its image as bowler-hatted, pinstriped and chinless with a fondness for champagne," David Gore-Booth wrote in 1999, as he prepared to leave a posting in Delhi.

"Indeed cocktail parties are death as, I am sure 99 per cent of diplomatic service colleagues would agree," Gore-Booth wrote, bemoaning the countless receptions ambassadors are expected to host, or attend.

The Foreign Office ended the tradition of valedictory letters in 2006, after a message from Ivor Roberts -- Britain's departing ambassador to Italy -- was leaked to the media.

Roberts criticized the ministry's management culture, and fondness for buzzwords. "Can it be that in wading through the plethora of business plans, capability reviews ... and other excrescences of the management age, we have indeed forgotten what diplomacy is all about," he wrote.