* Clashes follow plan to close parts of steel plant
* Likely loss of 1,300 jobs
* Belgian PM meets unions
BRUSSELS, Jan 25 (Reuters) - Belgian police fired water cannons and pepper spray at masked protesters on Friday as a demonstration over job losses at ArcelorMittal's Liege steel plant turned violent.
Masked protesters threw broken paving stones at police who were barricading a street leading to the residence of Belgian Prime Minister Elio Di Rupo. Traffic in much of central Brussels was paralysed.
Di Rupo on Thursday cancelled a trip to a summit in Latin America to meet with union leaders after ArcelorMittal, the world's biggest steelmaker, said it would shut facilities at Liege, in the east of Belgium, with the likely loss of 1,300 jobs.
The company, led by Lakshmi Mittal, one of Britain's richest men, said it had decided to close the coke mill and six finishing lines permanently after European demand for steel dropped by 8 to 9 percent last year.
About 350 workers gathered outside the prime minister's residence in central Brussels, according to police.
"We will lose our jobs next week. We want to make the politicians aware," said Jean Claude Fitipaldi, 35, an electrician at the Liege plant, as he watched the clashes.
It is a further blow for Belgium after last October's announcement that Ford Motor Co would close its car plant in Genk, some 40 km (25 miles) north of Liege, by the end of 2014.
Planned car plant closures, also including Opel in Bochum , have convinced ArcelorMittal that European steel demand will not return to pre-crisis levels.
"If we don't react quickly, it means the end of the steel industry in Liege," Jean-Luc Rader, a representative of the socialist FGTB union, said before going in to meet the prime minister.
Di Rupo and ministers met with union leaders during the clashes.
"There is less and less confidence in Mr Mittal, because after so many promises and then so many very huge decisions, it is quite difficult to discuss with him," Foreign Minister Didier Reynders said on his arrival.
In France, ArcelorMittal has promised there will be no forced layoffs after the French government threatened to nationalise its plant in Florange after it announced the idling of two blast furnaces.
There was no indication of a comparable compromise in Belgium. (Reporting by Ben Deighton; editing by Philip Blenkinsop and Jane Baird)