March 7 (Bloomberg) -- Protesters seeking to oust Thailand's Prime Minister Thaksin Shinawatra will ``surround'' his office before a cabinet meeting next week and plan an earlier protest outside Singapore's embassy in Bangkok.

As many as ``100,000 people'' will march from Sanam Luang park in downtown Bangkok to Government House on the morning of March 14, said Sondhi Limthongkul, a protest leader. Protesters have vowed to hold rallies every night until Thaksin resigns.

``Thaksin has challenged us, that we are good only during the night,'' Sondhi said in a speech broadcast late yesterday on local television station Channel 3. ``We want to show him that we are also very strong during the day.''

Thaksin, 56, a former policeman and billionaire businessman turned politician, on Feb. 24 dissolved parliament and called an election for April 2. Thailand's three main opposition parties plan to boycott the poll because of disagreements over constitutional change.

The Thai leader has faced escalating calls to quit since his family's sale of its stake in communications company Shin Corp. to Singapore's Temasek Holdings Pte in January netted a tax-free $1.9 billion. The sale was exempt from capital gains tax because the transaction went through the Thai stock exchange.

Since winning a record majority in Feb. 2005, Thaksin has been attacked over issues including conflicts of interest, media freedom, ministerial ethics, education reforms, free trade pacts, planned sales of shares in public utilities, and Muslim unrest.

Advanced Info

Advanced Info Service Pcl, Shin Corp.'s largest unit and Thailand's biggest mobile-phone operator, said today domestic consumers' opposition to the sale of the company to Temasek via the Shin transaction is hurting its sales. The company signed up 9.9 percent less subscribers in January from December.

``Our business has nothing to do with politics but the public opinion trend is there,'' Chamnarn Maytapreechakul, Advanced Info's newly appointed executive vice president for marketing, told reporters in Bangkok today. ``The current trend is a weakness for us at this point. This is a problem that we have to solve and it will take some time.''

Somsak Kosaisuk, a member of the People's Alliance for Democracy, today delivered a letter to Singapore's embassy in Bangkok asking the city-state's Prime Minister Lee Hsien Loong to cancel Temasek's purchase of the Shin stake.

``Otherwise the group will campaign and protest against Singapore's benefit, including asking Thai consumers to stop using the service of Shin,'' part of the letter said, according to Manager Daily, a newspaper owned by Sondhi, a media magnate and Thaksin's former friend. ``The sale of Shin's shares is the sale of national strategic business to foreigners. The group will come back on March 9 to demand the answer to this letter.''

Foreign Ownership

The Jan. 23 Shin Corp. sale to Temasek, a Singapore government-owned investment fund, happened the same month that Thailand raised the foreign ownership limit on telecommunications companies to 49 percent from 25 percent.

Ho Ching, Singapore Prime Minister Lee's wife, is the head of Temasek. Bernard Baker, a spokesman at Singapore's Ministry of Foreign Affairs, didn't reply to a voicemail left at his office today. Eva Ho, a spokeswoman for Temasek, declined to comment.

Morgan Stanley, the third-biggest U.S. securities firm by market value, today cut its 2006 economic growth forecast for Thailand on ``political uncertainty that is likely to delay investment recovery.'' Andy Xie, chief Asia economist at Morgan Stanley in Hong Kong, reduced his forecast to 4.9 percent from 5.4 percent, according to an e-mailed note to clients.

Stocks Decline

Thailand's stock index fell for a second day amid concern that the political unrest will hurt economic growth. The SET Index lost 1.7 percent to 738.36 at the 4:30 p.m. close in Bangkok, the biggest drop since a 2.1 percent decline on Feb. 2. Overseas investors today sold 792 million baht more of Thai stocks than they bought, the first day of net selling in seven.

``A stable political situation is very important for foreign companies' investment decisions,'' Ichiro Fukue, executive vice president of Mitsubishi Heavy Industries Ltd., said in an interview in Bangkok yesterday. ``Stable government is needed for long-term policies.''

A consortium of Mitsubishi Heavy, Mitsubishi Corp. and Sino-Thai Engineering & Construction Pcl yesterday signed a $322 million contract with state-owned EGAT Pcl to build a gas-fired power plant in Bangkok. Fukue attended the signing ceremony.

Workers at state utilities such as electricity and water companies are considering a strike as part of the campaign to force Thaksin's resignation, said Somsak, who is also secretary general of the State Enterprises Labor Relations Confederation.

To contact the reporters on this story: Beth Jinks in Bangkok at bjinks1@bloomberg.net; Anuchit Nguyen in Bangkok at anguyen@bloomberg.net.

Last Updated: March 7, 2006 07:05 EST