SEOUL/FRANKFURT (Reuters) - LG Electronics said Miele was infringing patents for so-called steam washing machines and has sent a letter demanding that the German domestic appliance maker stop using the technology, setting an end-October deadline for a response.

Miele has been and is willfully infringing on LG's patents, LG said in the letter, sent last week and seen by Reuters.

"In the interest of finding an amicable resolution of this matter, we are open to having an in-person meeting in November to discuss how to resolve this matter," the company wrote.

Miele, whose roots go back to 1899 when Carl Miele and Reinhard Zinkann founded a company to manufacture dairy cream separators, confirmed it had received the letter.

"Miele will examine the facts and answer in the required way," a Miele spokeswoman said in a statement, declining to give further comment for the moment.

The global washing machine market is expected to grow 2 percent this year to 123 million units, while sales are seen down 1 percent to $44 billion, market research firm GfK says.

LG said it holds more than 500 patents worldwide, related to the use of steam in its washing machines, including in Europe, the United States, South Korea and China.

Steam washing machines use less water and are therefore more energy-efficient. LG said Miele was violating "a considerable number" of its patents.

"LG respects intellectual property rights and the company will adopt proper legal measures to defend both our reputation and the rights to our exclusive technology," the company said in a statement to Reuters.

Privately held Miele reported a 6 percent increase in sales to 3.7 billion euros ($4 billion) for its fiscal year ending June 30, of which 2.6 billion came from outside its home market of Germany.

(Reporting by Harro ten Wolde and Eric Auchard in Frankfurt and Se Young Lee in Seoul, editing by David Evans)