* Protest leader had suggested a televised debate with the PM
* Pressure for talks grows, with deadly attacks on the increase
* Army chief noncommittal on possibility of a military coup
* Protest numbers dwindling, many ministries back at work
* Economy suffering; factory output drops in January (Recasts with protest leader saying will clear streets, edits)
By Amy Sawitta Lefevre and Pracha Hariraksapitak
BANGKOK, Feb 28 (Reuters) - Anti-government protesters will clear their camps from main roads they have blockaded in the Thai capital since mid-January but step up efforts to oust the government by trying to shut down ministries, their leader said on Friday.
The protesters have been trying since November to push out Prime Minister Yingluck Shinawatra and eradicate the political influence of her brother, ex-premier Thaksin Shinawatra, seen as the real power in Thailand.
But their numbers have dwindled and attacks on the various camps with grenades and guns have become an almost daily occurrence. Three people were killed when a grenade was thrown into a busy shopping area near one camp on Sunday.
"We will stop closing Bangkok and give every intersection back to Bangkokians. We will stop closing Bangkok from Monday," protest leader Suthep Thaugsuban told supporters on Friday. "But we will escalate our shutdown of government ministries and Shinawatra businesses."
All his supporters are to move inside Lumpini Park in the heart of the capital, where many of them already sleep in tents. A government complex in the north of the city would remain under the control of an allied group, he said.
Sophon Pisutwong, a police commissioner with the body overseeing a state of emergency in Bangkok, said protesters had managed to shut 82 ministries or state agencies since November but, as of Friday, 63 had reopened, including the finance ministry.
Earlier on Friday, Labour Minister Chalerm Yoobamrung rejected a proposal from Suthep that he and Yingluck should hold a televised debate
"Yingluck is the legitimate leader of the country and Suthep is a man with warrants for his arrest who heads an illegal movement. The prime minister should not talk to Suthep," Chalerm said.
"Suthep is only proposing negotiations, even though he dismissed them before, because protest numbers are dwindling."
The crisis is hurting the economy, with confidence and domestic demand both down. Data on Friday showed factory output fell 6.41 percent in January from a year before.
In some good news for the government, China is to buy 400,000 tonnes of Thai rice, providing funds to help pay farmers who have been protesting because a state rice-buying programme has run out of money.
On Feb. 4, China scrapped a deal to buy 1.2 million tonnes of rice because of an investigation by the Thai anti-graft agency into various deals between Thailand and China.
On Thursday Yingluck was served with charges of negligence relating to the rice programme. The case could eventually see her forced from office.
Army chief General Prayuth Chan-ocha, asked by reporters if recent violence would trigger a coup, remained noncommittal and expressed exasperation at the question being put to him time and again.
"We must not discuss this every day," he said. "I can't promise whether there will be a coup or not."
Talk of a possible civil war has also picked up recently but Prayuth said he doubted that outcome. "We must control the situation using the law," he said.
MORE VOTING ON SUNDAY
The crisis broadly pits Bangkok's middle-class and southern opposition supporters, backed by the royalist establishment, against the largely rural supporters of Yingluck and Thaksin.
After a period of calm following Yingluck's election win in 2011, opposition swelled when her government tried to push through a political amnesty that would have let Thaksin return from self-imposed exile without having to serve a jail sentence for graft. He says the charges were politically motivated.
Thaksin was toppled by the army in 2006. The military has tried to stay above the fray this time but Yingluck is still facing multiple challenges from the courts, which threw out two governments allied to Thaksin in 2008.
Yingluck called an election for Feb. 2 to try to end the latest crisis but it was disrupted by the protesters.
The Election Commission will try to hold polls on Sunday in five provinces where voting was not completed. Election re-runs planned for April in other provinces have been suspended pending a court decision on procedures.
The protesters want to set up a "people's council" of unspecified worthy people to force through political and electoral changes before a new general election is held, hoping that will stop parties loyal to Thaksin from winning. (Additional reporting by Kittipong Thaicharoen, Pairat Temphairojana and Orathai Sriring; Writing by Alan Raybould; Editing by Robert Birsel)