MELBOURNE, Nov 25 (Reuters) - Rio Tinto Ltd (RIO) boss Jakob...

MELBOURNE, Nov 25 (Reuters) - Rio Tinto Ltd (RIO) boss Jakob Stausholm has made his first trip to Mongolia while in the top job to meet Prime Minister Luvsannamsrain Oyun-Erdene as Rio looks to revive a relationship that has soured over the development of a big copper mine.

Rio has faced costly delays at the underground expansion of its Oyu Tolgoi project that it has blamed on geotechnical difficulties and COVID-19, angering the Mongolian government and shareholders of developer Turquoise Hill Resources TRQ.TO in which Rio has a majority stake.

"This week for the first time since becoming Chief Executive, I was able to return to the beautiful wintry country of Mongolia, home to Oyu Tolgoi, the world’s largest greenfield underground copper mining project," Jakob Stausholm said in a post on LinkedIn on Wednesday.

As well as meeting with Oyun-Erdene, Stausholm engaged other ministers and members of parliament, "to hear and understand their concerns," he said.

"This was a vital first step in our relationship reset that engages based on trust and we are committed to earning it step by step," he said.

Rio last month delayed first production at the underground development of Oyu Tolgoi by three months to January 2023, after Turquoise had estimated additional funding required for the project had ballooned to $3.6 billion.

Delays to development of what will be one of the world's largest copper mines has antagonised the Mongolian government, which owns a 34% stake, and fuelled a funding spat between Rio and Turquoise Hill.