* Truck owners say union accepted 25.5 percent raise
* Union boss Moyano calls national strike next Wednesday
* Workers want government to reduce income tax burden
* President Fernandez and Moyano at odds over past year
By Helen Popper and Guido Nejamkis
BUENOS AIRES, June 21 Argentina's most powerful union leader, Hugo Moyano, called off a strike by fuel truckers on Thursday after securing a pay increase, but announced a one-day walkout next week to demand that President Cristina Fernandez cut taxes.
Striking truckers blocked fuel depots and refineries for a second day on Thursday, sparking shortages at gas stations and some homes in one of the biggest trade-union challenges to Fernandez in her five years in office.
Drivers left picket lines after Moyano, head of the CGT labor federation, agreed to a 25.5 percent pay rise with haulage company bosses, and local media said fuel supplies should be back to normal within 48 hours.
However, the truckers are also pushing for Fernandez to raise the income tax floor as inflation eats into wages.
"We always said that a pay rise wouldn't be enough," said Pablo Moyano, Hugo Moyano's son and another top leader of the truckers' union, which is feared for its capacity to bring Latin America's third-largest economy to a standstill.
"We're going to continue staging surprise strikes in different sectors until the government changes its policy of continually cutting into workers' wages," he said.
Hugo Moyano described Fernandez as "arrogant" and called a national truckers strike and a day of protests for next Wednesday.
Other unions belonging to the CGT said they would also take part.
The three-day strike by fuel truckers had been due to end at midday on Friday, by which time many service stations would likely have run out of automobile fuel.
Fernandez, a combative center-leftist, returned from an overseas trip early on Wednesday due to the protest.
She deployed military police to guard fuel plants blockaded by truckers and implemented emergency supply plans in an effort to avert shortages, a situation not seen since a rebellion by farmers in 2008.
Moyano used to be a close ally of the president but their strategic alliance collapsed over the last year.
Loathed by many middle-class Argentines, the burly truck driver will seek a third term as president of the CGT federation in an election next month.
Fernandez's administration filed a criminal complaint over the strike and fined the truckers' union four million pesos (about $888,000) for defying an order to negotiate.
"This is a humanitarian issue," Planning Minister Julio De Vido told a news conference before the protest was lifted.
He said whole rural communities had been left without household gas supplies at the start of the southern hemisphere winter and said several northern provinces and key highways were virtually without automobile fuel.
Argentina is one of the world's biggest exporters of grains and the vast majority of farm goods are sent to port by truck. Farmers, who are nearing the end of this season's soy and corn harvest, are also major consumers of fuel.
Annual inflation estimated at about 25 percent is stoking labor unrest as the economy cools after a long boom.
Surging prices have also fueled capital flight and eroded the competitiveness of Argentine goods, prompting Fernandez to slap unorthodox curbs on imports and foreign currency purchases that are riling importers and the middle class.
The strike also reflected jostling for position within the CGT federation ahead of next month's leadership elections and within Fernandez's ruling and fragmented Peronist party, analysts say.
"There's a struggle going on within Peronism that stems from the president's strategy to accumulate and concentrate her personal power since her re-election," said Pascual Albanese of the Institute of Strategic Planning think-tank.
Fernandez, who won a second term by a landslide in October, is unable to run again in 2015 unless the constitution is changed. She controls Congress but might struggle to get the two-thirds support needed to change the country's charter.
There are signs of a nascent succession struggle in her party, which has traditionally had close ties with the unions.
That could deepen the conflict with Moyano, who local media have suggested is forging closer ties with Daniel Scioli, a moderate Peronist who runs the country's biggest province and is seen as a potential successor to Fernandez.
"When a conflict has a political objective, it's difficult to imagine that it won't end up escalating," said local pollster and analyst Sergio Berensztein.