UPDATE 1-Brazil's Gerdau posts 48% fall in fourth quarter profit on lower steel sales

(Adds details and context in paragraphs 2-6)

SAO PAULO, May 2 (Reuters) - Brazilian steelmaker Gerdau posted on Thursday a 47.9% decrease in its adjusted net profit for the first quarter from the same period a year earlier, affected by lower steel sales amid higher imports in Brazil.

It reported a 1.25 billion reais ($244.6 million) adjusted net profit for the three-month period ended in March.

Gerdau, which has most of its business in Brazil and North America, posted a net revenue decline of 14.1% year-on-year, as steel sales fell 8.6% in volume, with the company attributing the performance to "excessive imports in the Brazilian market".

However, the firm welcomed Brazil's

government decision

in late April to establish import quotas for 11 steel products and to impose higher taxes on them when those volumes are exceeded, dubbing the move "an important progress" in the commercial defense of the national steel industry.

Gerdau said the measure would encompass about 25% of the volume it sells in Brazil.

It posted adjusted earnings before interest, taxes, depreciation and amortization (EBITDA) of 2.81 billion reais, down 34.9% from a year earlier, while adjusted EBITDA margin declined 5.5 percentage points to 17.4%.

($1 = 5.1109 reais) (Reporting by Andre Romani; editing by Steven Grattan)