* 77 pct rally in China steel prices prompts jump in output
* Some mills boost production ahead of upcoming mandated cuts
* 'Zombie' mills rise again, calls for self-discipline unheeded
* China risks trade response from U.S., others
By Ruby Lian and Manolo Serapio Jr
SHANGHAI/MANILA, April 21 (Reuters) - The rest of the world's steel producers may be pressuring Beijing to slash output and help reduce a global glut that is causing losses and costing jobs, but the opposite is happening in the steel towns of China.
While the Chinese government points to reductions in steel making capacity it has engineered, a rapid rise in local prices this year has seen mills ramp up output. Even "zombie" mills, which stopped production but were not closed down, have been resurrected.
Despite global overproduction, Chinese steel prices have risen by 77 percent this year from last year's trough on some very specific local factors, including tighter supplies following plant shutdowns last year, restocking by consumers and a pick-up in seasonal demand following the Chinese New Year break.
Some mills also boosted output ahead of mandated cuts around a major horticultural show later this month in the Tangshan area. Local mills must at least halve their emissions on certain days during the exposition, due to run from April 29 to October.
China, which accounts for half the world's steel output and whose excess capacity is four times U.S. production levels, has said it has done more than enough to tackle overcapacity, and blames the glut on weak demand.
But a survey by Chinese consultancy Custeel showed 68 blast furnaces with an estimated 50 million tonnes of capacity have resumed production. The capacity utilization rate among small Chinese mills has increased to 58 percent from 51 percent in January. At large mills, it has risen to 87 percent from 84 percent, according to a separate survey by consultancy Mysteel.
The rise in prices has thrown a lifeline to 'zombie' mills, like Shanxi Wenshui Haiwei Steel, which produces 3 million tonnes a year but which halted nearly all production in August. It now plans to resume production soon, a company official said, declining to be named as he's not authorised to speak publicly.
Another similar-sized company, Jiangsu Shente Steel, stopped production in December but then resumed in March as prices surged, a company official said.
More than 40 million tonnes of capacity out of the 50-60 million tonnes that were shut last year are now back on, said Macquarie analyst Ian Roper. "Capacity cuts are off the cards given the price and margin rebound," he said.
Profit margins have risen to 500-600 yuan a tonne ($77-$93) on average, the highest in at least two years, said Hu Yanping, senior analyst at Custeel.com.
"The government wants to bolster the economy and boost demand for industrial sectors, but it is also resolute to push forward the supply-side reform, putting it in a dilemma," said Hu.
To show the world it is serious in slicing its bloated steel sector, China has said it cut 90 million tonnes of capacity and plans to cut another 100-150 million tonnes through 2020.
Yet China's crude steel output hit a record high of 70.65 million tonnes in March.
ANGER AT EXPORTS
A surge in steel output should be driven by an increase in contracted purchases, otherwise mills are just betting on an improvement in demand that may not happen, Liu Zhenjiang, vice secretary general of the China Iron and Steel Association (CISA), told an industry conference in Beijing this month.
"Cutting steel capacity is important, but controlling steel output is more important," he said.
CISA, which groups China's biggest steel firms including Baoshan Iron and Steel, has consistently urged its members to show "self-discipline" and not increase output at the first sign of rising prices, a plea that's usually gone unheeded.
On Tuesday, the United States, European Union and others called for urgent action to address global steel overcapacity, a day after China and other major steel producing nations failed to agree on measures to tackle an industry crisis.
Britain in particular has been hit hard as its largest producer Tata Steel has announced plans to pull out of the country, threatening 15,000 jobs. Last week, more than 40,000 German steel workers took to the streets to protest against dumping from China.
Anger towards China grew louder since last year as its steel exports surged to a record 112 million tonnes, but the domestic steel price rally could help limit shipments this year as producers sell more at home.
Some private mills have defaulted on export contracts signed a month before shipping because of the rapid rise in domestic prices, according to a trader with knowledge of the situation.
Others have delayed deliveries for export orders and cut their export targets, the trader said.
The world could benefit if China's steel production reverts to 2011 levels when the surplus, or the gap between output and consumption, was just 34 million tonnes, said BMI Research commodities strategist Mitchell Hugers.
"It's not the capacity cuts that matter, it's the amount of exports that matter," he said.
($1 = 6.4683 Chinese yuan)
(Additional reporting by David Stanway in Beijing; Editing by Gavin Maguire, Ian Geoghegan and Lincoln Feast)