PYEONGCHANG (REUTERS) - US Vice-President Mike Pence made only a brief appearance at a reception marking the start of the Winter Olympics on Friday (Feb 9), avoiding a potentially awkward encounter with the ceremonial leader of North Korea attending the same event.

The reception hosted by South Korean President Moon Jae In in the mountain resort of Pyeongchang was the culmination of months of work by Seoul, which seeks to use the Olympics to ease tension spurred by North Korea's pursuit of nuclear weapons.

Ahead of the reception, South Korean media said Mr Pence was expected to be seated opposite Mr Kim Yong Nam, North Korea's nominal head of state, at the 12-seat head table.

However, South Korea's presidential Blue House said Mr Pence had a meeting scheduled with US athletes and had planned to stay only briefly to greet other officials.

Mr Pence shook hands with other leaders, including close ally Japanese Prime Minister Shinzo Abe, but not Mr Kim Yong Nam, according to a Blue House pool report.

Earlier on Friday, Mr Pence said Mr Moon gave his backing to additional measures the United States is planning to try to curb North Korea's missile and nuclear programmes.

Mr Pence spoke after paying tribute at a memorial for 46 South Korean sailors killed in the sinking of a warship in 2010 that Seoul blamed on a North Korean torpedo attack.

Mr Kim Yong Nam landed in South Korea on Friday along with leader Kim Jong Un's younger sister, Ms Kim Yo Jong, aboard her brother's private jet.

The white aircraft had the Democratic People's Republic of Korea, North Korea's official name, inscribed in black in Korean on its side, followed by the North Korean flag.

Ms Kim Yo Jong and her delegation were greeted by government officials, including Unification Minister Cho Myong Gyon, before boarding a bullet train to Pyeongchang. A special train had been prepared just for the visitors, a Blue House pool report said.

Smiling and seemingly unfazed by cameras flashing during the airport meeting, Ms Kim Yo Jong wore a black coat, matching ankle boots and carried a black purse. Dozens of South Koreans at the airport tried to snap photographs of her on their mobile phones.

She is the first member of North Korea's ruling family to visit the South, while Mr Kim Yong Nam is the most senior North Korean official to make a cross-border trip.

The pair will have lunch with Mr Moon on Saturday, Mr Moon's office said.

Mr Pence had kept open the possibility for some contact with the North Koreans in South Korea, while reiterating Washington's insistence that denuclearisation by North Korea is a necessary condition for peace.

Mr Pence, Ms Kim Yo Jong and other world leaders will attend the opening ceremony in Pyeongchang, just 80km from the heavily fortified border between North and South Korea, later on Friday.

Hundreds of anti-North Korea protesters scuffled with riot police hours not far from the main stadium before the opening ceremony was due to begin, with some of their banners reading "Moon regime is leading Korea to destruction".

Thousands of spectators, including a squad of more than 200 North Korean cheerleaders, filled the frigid stadium awaiting the start of the opening ceremony, when the two Koreas will march together under one peninsula flag for the first time in more than a decade.

"It is not as cold as I expected. It is a blessed day. I like the reconciliatory mood and I have high expectations," said Mr Kim Sang Yoon, a 44-year-old businessman who drove nearly five hours to see the opening ceremony with his wife and two sons.

Nearly 500 North Koreans have arrived in South Korea for the Olympics, which run through to Feb 25.