BRUSSELS, Belgium | The world's largest steelmaker ArcelorMittal SA said Wednesday it agreed to buy Venezuela-based Unicon, a maker of steel pipes for the oil and gas industry, adding to a string of recent South American acquisitions.

The company did not say how much it would pay for Unicon, which employs 2,445 people at six plants in Venezuela and shipped 552,000 metric tons for the year ended March 2007.

"Unicon is an excellent company, commanding a leading position in Venezuela. This highly complementary acquisition will help us expand our position in the fast-growing Americas market," said AcelorMittal chief financial officer Aditya Mittal.

Luxembourg-based ArcelorMittal wants to increase steel shipments by more than a fifth by 2012 as it pushes into Latin America, Africa, Eastern Europe, Russia and Central Asia, claiming worldwide demand for steel is "buoyant."

Demand for steel in those regions is booming as their economies expand, calling for more steel to construct buildings, machines and cars -- just as Europe and North America face weaker growth and tougher competition from Asian imports.

ArcelorMittal in December bought Argentina's largest steel distributor M.T. Majdalani y Cia. SA, which sells flat stainless steel products. And in October, it paid $542 million to buy a third of Argentine steel company Acindar that it did not already own.

It has also pledged to spend up to $1.75 billion to buy out Brazilian specialty steel unit ArcelorMittal Inox Brasil SA, formerly known as Acesita.

The bid for Inox Brazil would give ArcelorMittal total control over both of Arcelor SA's main Latin American units after Brazilian regulators forced it to spend up to $5.4 billion to buy out Arcelor Brasil as part of Mittal Steel Co. NV's takeover of Arcelor that formed ArcelorMittal.