Samsung Techwin is facing a barrage of criticism following a recent investigation by the prosecution on allegations that the company was installing used parts for assembling critical artillery weapons.

On Thursday, the special investigation team of the Changwon district prosecutor’s office raided the manufacturing plants of Samsung Techwin that produce K-9 guns, and also the Defense Agency for Technology and Quality.

The investigation, requested by of the Board of Audit and Inspection, was based on allegations that Samsung had installed used parts to manufacture K-9s, which are self-propelled artillery guns that Samsung Techwin supplied to the Armed Forces between 2008 and 2010.

The parts in question are regarded as a core driving force of the weapon, which was developed by Samsung on the growing demand for artillery to deter North Korea. Costing about 3.9 billion won ($3.6 million) per unit, the guns were put into combat starting in 2000 upon an agreement with the Defense Ministry.

Samsung claims that it was forced to use the used parts due to the local defense industry laws stipulating that manufacturers may acquire only the exact number of parts coinciding with the end number of products. In other words, should a company churn out 10 guns, it can acquire only 10 core parts.

“There are certain legal limitations that must be addressed,” Samsung officials said.

If a part malfunctions, the company must replace it with a used one, according to Samsung sources. They also claimed that less than 1 percent of such parts were used to assemble the guns.

Officially, the company had no comment as the probe is still ongoing.

However, the public outcry over the latest charges against Samsung may not die down easily, industry sources said, citing past problems the guns had manifested.

In 2010, Samsung Techwin and the K-9 guns came under attack for failing to work properly during the 2010 North Korean attack on Yeonpyeong Island in the West Sea.

Samsung Techwin reportedly relies on more than 30 percent of its sales on defense weapons including the K-9 guns.

The latest probe follows another one conducted on Samsung Techwin last year for internal corruption issues. The chief executive at the time was forced to step down.

By Kim Ji-hyun (jemmie@heraldcorp.com)