BEIJING: US President Barack Obama's first visit to China will undoubtedly be marked by difficult talks on trade and climate change, but another thorny issue has emerged: how to write "Obama" in Mandarin.

While the Chinese have written "Aobama" since the US leader first emerged on the political scene, US officials want "Oubama" to be the new standard transcription, as the characters more closely match theEnglish pronunciation.

The Olympic Games held here last year may have influenced the Chinese on the spelling issue, as the character "ao" -- which means "mysterious" or "secret" -- is also used in the expression for the Games, "Aolinpike".

But in recent days, ahead of Obama's arrival in China on Sunday, theUS embassy began using the phonetic transcription "Oubama" on its website -- which is already used in Taiwan and Hong Kong.

"Oubama is the official US government translation. We are trying to ensure consistency," embassy spokeswoman Susan Stevenson told AFP.

But on the Chinese foreign ministry website, the US president is still "Aobama", and Chinese media say enforcing a change of the transcription at this point may be a tough task for the White House.

A senior foreign ministry official who works on translation issues, quoted by the Legal Evening News, said "Oubama" is indeed correct.

Phonetic transcriptions are decided not by the foreign ministry, but by another governmental agency which issues an official manual on translating English names.

As for the president's first name, Chinese media have adopted several options including "Balake" and "Beilake".

Facetious Chinese bloggers have opted for something else altogether, creating "Maobama" or "Obamao" -- combinations of Obama and Chinese revolutionary leader Mao Zedong.