(Adds ambassador's comments)
SEOUL, July 15 (Reuters) - South Korea's coastguard said on Tuesday it had stepped up patrols near islands at the centre of a territorial dispute with Japan, a day after Seoul recalled its ambassador in anger at new Japanese claims to the rocky outcrops.
The fight over the desolate islands, known as Dokdo in Korean and Takeshima in Japanese, has been a persistent irritant in relations between the neighbours, rekindling memories in South Korea of Japan's 1910-1945 colonial rule over the peninsula.
"We're beefing up security measures in relation to Japan's decision to describe Dokdo as its territory in its textbooks," a coastguard official said.
On Monday, Tokyo said it had told Seoul it would refer in a middle school teaching guide to the islands as Japanese territory, triggering angry rallies outside Japan's embassy in Seoul and official protests from South Korea's government.
School textbooks, seen as an expression of government views in many Asian countries, sometimes lead to international spats. In 2005, thousands of Chinese took to the streets to protest what they said was Japan's whitewashing of its World War Two history in schoolbooks.
The disputed islands are controlled by South Korea, which keeps a police presence there, and lie roughly equidistant from the mainland of both countries.
South Korea's coastguard said in a separate statement on Tuesday that it had strengthened its early warning system, "as a preventive measure against any possible attempt by Japanese right-wing elements sailing to Dokdo."
The waters surrounding the islands are rich in marine life and popular with squid fishermen while the seabed in the area may have deposits of a natural gas hydrate that could be worth billions of dollars.
Japanese government spokesman Nobutaka Machimura on Tuesday called for a calm response to overcome differences.
"Right now Japan and South Korea have entered a new age, and efforts should be made not to interrupt this," he said.
Before returning to Seoul, South Korea's ambassador Kwon Chul-hyun, visited Japan's foreign ministry on Tuesday to lodge a protest, his embassy said in a statement.
Kwon said South Koreans may have a hard time welcoming Japanese Prime Minister Yasuo Fukuda for a trip planned in a few months to the country, adding Japan had more to lose than gain due to the island fight, the statement said.
The dispute is one of a number of long-running territorial rows involving Japan and its neighbours.
Last month, a row over ownership of another group of tiny islands called the Senkaku isles in Japan, the Diaoyu in China and the Tiaoyutai in Taiwan, flared up when a Japanese coastguard vessel collided with a Taiwan fishing boat, sinking it and injuring one person.
NO BENEFIT TO LEE
South Korean President Lee Myung-bak, who took office in February, pledged to better ties with major trading partner Japan after his predecessor Roh Moo-hyun tried to score points at home by fanning the flames of lingering anti-Japan sentiment.
Analysts said this recent development may add to prevailing unhappiness about the Lee regime.
The public is likely to see his call to get closer to Tokyo as just one more policy blunder for his new government, which has seen its support rate fall after bungling a U.S. beef deal and personnel appointments, Kang said.
"People tend to regard the Dokdo case as his diplomatic mistake or failure. Even though people are united against Japan, it is not likely to boost his popularity," said Kang Won-taek, a political science professor at Soongsil University in Seoul. (With additional reporting by Kim Junghyun in Seoul and Elaine Lies in Tokyo) (For related factbox see [ID:nT137120]) (Editing by Valerie Lee)