SEOUL, Oct 12 (Reuters) - Desperate to avoid military call-up to fight in Ukraine, more than 20 Russians have sailed in yachts down the North Pacific coast to South Korea, but most were refused entry, a South Korean lawmaker said on Wednesday.Arriving aboard four yachts, 23 Russians have reached South Korea since late September, but authorities have granted entry to only two, lawmaker An Ho-young said, citing coast guard data.Register now for FREE unlimited access to Reuters.comThe others "were rejected because their purposes were unclear and they did not have sufficient documents," the lawmaker said in a statement.Two other yachts remained in Pohang, and one of them - left with just two Russians aboard after two gained entry - intended making the long voyage to Thailand, the lawmaker added.A justice ministry official said he did not have details about the yacht cases, but Russians are in general allowed to enter the country without a visa as long as they obtain prior approval via South Korea's electronic travel authorisation system."