BANGKOK, Dec 13 (Reuters) - Thai stocks slipped to three-month lows on Friday, poised for a second week of falls, as the domestic political drift marred growth at home, while Indonesian shares hit a week-low on a tumbling rupiah and worries over U.S. stimulus tapering. At midday, the Thai SET index was down 1 percent at 1,342.97, its lowest since Sept. 6. Selling was most active in telecoms shares, led by top mobile phone operator Advanced Info Service which fell 1.9 percent to nine-month lows. The benchmark has fallen 1.4 percent so far in the week, taking its year-to-date loss to 3.5 percent, making its Asia's second worst performer, thanks to heavy foreign sell-offs. Foreign investors sold a net $2.4 billion of Thai shares since November to Thursday amid political turmoil in the country. Their net sales stood at $5.9 billion this year, much larger than in many neighbouring markets. Sentiment was weak near-term, partly due to uncertainty associated with the U.S. Federal Reserve meeting on Dec. 17-18. "Global sentiment was shaky ahead of the U.S. FOMC meeting next week, while the political situation at home is still in a deadlock," strategists at broker KGI Securities said in a report. "The key factor to watch is whether the general election on February 2, 2014 can happen. In the meantime, all factors point to continued foreign selling," they wrote. The leader of a protest group trying to overthrow Thailand's government said on Friday the prime minister should either step down or be forced out, and his movement would then need around a year to push through reforms. Indonesia's main index edged down 0.2 percent, earlier falling to its lowest since Sept. 6, as a falling rupiah dented sentiment. It fell to its lowest level in nearly five years. Large-caps, including Bank Rakyat Indonesia and Astra International, extended losses from the previous session. Foreign selling derailed the region this week, with stocks in the Philippines among the under-performers. The benchmark of 30 large-cap companies had fallen 4.3 percent so far on the week. For Asian Companies click; For South East Asia Hot Stock reports, click; SOUTHEAST ASIAN STOCK MARKETS Change at 0639 GMT Market Current Prev Close Pct Move TR SE Asia Index* 388.75 390.23 -0.38 Singapore 3059.91 3059.04 +0.03 Kuala Lumpur 1841.59 1833.87 +0.42 Bangkok 1342.97 1356.21 -0.98 Jakarta 4202.06 4212.22 -0.24 Manila 5754.04 5762.53 -0.15 Ho Chi Minh 507.46 506.92 +0.11