KYIV, Feb 16 (Reuters) - Russia said it had broken through two of Ukraine's fortified defence lines in the east of the country, while Western countries announced more military spending on Ukraine, including artillery rounds, as Kyiv warned of continued Russian attacks.

Bolstered by tens of thousands of reservists drafted in December, Russia has intensified attacks across southern and eastern Ukraine in recent weeks, and a major new offensive is widely anticipated as the first anniversary of its invasion nears.

The Russian Defence Ministry on Wednesday said Ukrainian forces had retreated in the face of Russian operations in the Luhansk region, although it gave no details and Reuters was not able to independently verify this and other battlefield reports.

"During the offensive ... the Ukrainian troops randomly retreated to a distance of up to 3 km (2 miles) from the previously occupied lines," the ministry said on the Telegram messaging app.

"Even the more fortified second line of defence of the enemy could not hold the breakthrough of the Russian military."

The ministry did not specify in which part of the Luhansk region the offensive took place.

Later on Wednesday, Ukrainian deputy defence minister Hanna Malyar said Russian forces were mounting "round-the-clock" assaults on government positions, without specifying where.

"The situation is tense. Yes, it is difficult for us. But our fighters are not allowing the enemy to achieve their goals and are inflicting very serious losses," Malyar wrote on Telegram.

In Kyiv, the capital's military administration said six Russian balloons that may have contained reconnaissance equipment were shot down over the city on Wednesday after air raid sirens blared.

"The purpose of launching the balloons was possibly to detect and exhaust our air defences," it said on the Telegram messaging app. Russia did not immediately comment.