* Nikkei down 1 percent, Topix falls 0.8 pct
* Losses in other Asian markets sour sentiment in Tokyo
* Volume at 2-mth lows ahead of Christmas
By Ayai Tomisawa and Antoni Slodkowski
TOKYO, Dec 20 (Reuters) - Japan's Nikkei dropped 1 percent in thin trade on Monday, with sentiment soured by declining Asian markets.
Asian shares eased, lead by a 0.8 percent drop in the Seoul market <
> as tensions heightened on the Korean peninsula."Selling is due to external reasons, and as there are fewer foreign participants in the market, low volume is causing volatility," said Hideyuki Okoshi, general manager at Chuo Securities.
The Nikkei <
> fell 1 percent, or 107.50 points, to 10,196.47, coming closer to resistance at 10,116.53, the level of its 25-day moving average, a gauge frequently used by Tokyo investors.The broader Topix index <
> declined 0.8 percent to 896.30.China's key stock index fell 3 percent late on Monday morning, with a shortfall of money flows ahead of the year-end amid a tight monetary environment pressured the market.
Shanghai's composite index <
> dropped to 2,804.6 points by midday after edging lower nearly every day last week. [ ]After hitting its highest closing level since May last Tuesday, the Nikkei stayed flat for the rest of the week as domestic investors aggressively took profits on its rally of around 12 percent since the beginning of November, while foreign investors continued buying financial shares seen as undervalued.
"Generally, with exchange rates steady and no big negative factors, there are no major incentives for the Nikkei to move in either direction," said Mitsushige Akino, general manager at Ichiyoshi Investment Management.
LOW VOLUME
Trading volume was at its lowest in nearly two months, with around 1 billion shares changing hands on the Tokyo Stock Exchange's first section at 0406 GMT, putting it on course to stay well below last week's closing average of around 2.1 billion shares.
Market players said volumes may dry up further this week as foreign investors who have been net buyers of Japanese equities for the last six weeks, helping push the index higher, will be less active as the Christmas holidays approach.
"There are high expectations for Japanese equities to do well in January-March so investors won't rush to take profits either, helping the Nikkei stay around the 10,300 level," Akino said.
Baby goods maker Pigeon Corp <7956.T> rose 2.3 percent to 2,793 yen after Credit Suisse started coverage of the company with an "outperform" assessment.
Honda Motor <7267.T> rose 0.8 percent to 3,260 yen after saying on Friday it would target sales in China of 730,000 vehicles in 2011, for growth of more than 10 percent from the 650,000 estimated for this year. [
]Tokyo shares face strong technical resistance at 10,420.74, the level where futures and options contracts expiring in December settled earlier this month, traders said.
Although Yumi Nishimura, a senior market analyst at Daiwa Securities Capital Markets, said that if there was some positive news later in the week, such as a softening of the yen against the dollar, the Nikkei could quickly spike to around 10,500 before the end of the year.
Tokyo investors were closely monitoring the situation on the Korean peninsula, where North Korea's military has raised an alert for some artillery units ahead of a planned live-fire drill by South Korea. [
]A five-notch downgrade of Ireland by Moody's and budget warnings by the International Monetary Fund on Friday reminded markets of ongoing euro zone debt woes, and worries over Europe will likely weigh on market sentiment in the last two weeks of 2010. (Editing by Joseph Radford)