Canals to Caspian Sea too small for big boat so Gurbanguly Berdymukhamedov accepted more modest 'gift' of £50m vessel according to leaked US embassy cables

President Gurbanguly Berdymukhamedov is "vain, suspicious, guarded, strict, very conservative", a "micro-manager" and "a practised liar", US diplomats say, in a stunningly unflattering portrait of Turkmenistan's head of state

In the diplomatic equivalent of a mauling, the US embassy gives a brutal assessment of the president's talents, and those of his ruling family. Berdymukhamedov became ruler of the oil-rich former Soviet nation – known for its megalomanic leaders – in 2006.

The cable, released by WikiLeaks but originally sent by Sylvia Reed Curran, the US's charge d'affaires in Ashgabat, Turkmenistan's capital, fleshes out Berdymukhamedov's humble family background.

She says he is the only son in a family of eight children. She adds witheringly: "His father is a retired prison guard with the rank of colonel. The father, many in Turkmenistan think, is more intelligent than the son."

The cable says the president reportedly has two different families – ith two daughters and a son from his Turkmen spouse and a daughter with his Russian mistress. His Russian partner – identified as Marina – has a 14-year-old daughter with the president. Berdymukhamedov's wife has been reportedly living in London since 2007, it adds. Several nephews are murkily involved in business, it adds.

Recalling his early career in a dental clinic, one source describes the president as someone who "never forgets". He is also "very clean and neat" and requires all around him "to be the same." When Berdymukhamedov became head of the clinic "he insisted that the other men who were there had creases in their pants", the cable reports.

Its most damning section reads as follows: "Berdymukhamedov does not like people who are smarter than he is. Since he's not a very bright guy, our source offered, he is suspicious of a lot of people." The president "did not like America, Iran or Turkey but likes China", it adds.

In a separate cable from the embassy in Ashgabat, diplomats reported that the president wanted a giant yacht like Roman Abramovich but had to settle for one small enough to reach the Caspian Sea.

Gurbanguly Berdymukhamedov received a €60m (£50m)yacht as a "gift" from the Russian gas and resources company Itera. He was so pleased with his new toy that in September 2008 he held a cabinet meeting on board.

"President Berdymukhamedov appeared in one photograph sporting a navy blue sailing cap, a French-style white-and-blue striped shirt and binoculars hanging around his neck," said a cable from the US embassy.

Unfortunately nobody knew how to sail the Italian-made yacht, named Revival. The problem was quickly solved with a call to a Swedish-owned shipping firm. It was bluntly told to provide "a master, a chief mate and a chief engineer", the cable says.

One unnamed expatriate source told the US: "The president had originally wanted a larger yacht similar to one owned by Russian oligarch Roman Abramovich, but that yacht would not fit through the canals leading to the Caspian Sea and thus Berdymukhamedov had to settle for this one."

Intriguingly, the same source added that the president's "pool of automobiles consists of a Bentley, a Mercedes Mayback (gift of a German company), a Range Rover, and a Cadillac Escalade".

The president's son-in-law, though, got a rap on the knuckles after acquiring too many fancy homes in London, one cable reveals.

Dovlet Atabayev was the subject of an internal investigation. "Supposedly the young man is in trouble for having acquired some nice real estate in the London area."

Atabayev is the head of the London office of Turkmenistan's state agency for oil and gas. He was one of several officials who had "got into hot water" for alleged "ostentatious corruption", US diplomats said.