Ukrainian Armed Forces engineering units and construction companies of the Luhansk, Zhytomyr and Khmelnytsky regions are working in the Luhansk area, the army operation press center said on Tuesday.

"Workers from various regions of Ukraine supervised by military specialists are beefing up fortifications along the contact line. Our defense lines are being equipped with earth-and-timber emplacements, aircraft shelters and dugouts. Both timber and ferroconcrete are being used," said a report posted by the press center on Facebook on Tuesday.

"Fire nests and dugouts are being built following blueprints of the Ukrainian Armed Forces Kyiv Military Design Institute. Earth-and-timber emplacements have been tested at the Zhytomyr range. They can withstand attacks by 150mm artillery guns," the press center said.

"The builders are working twelve hours a day"; they are fully equipped with hardware, it said.