An armored carrier, imitating an enemy vehicle, drives during military exercises conducted by Ukrainian armed forces at the Shiroky Lan training ground in Mykolaiv region, Ukraine, in this October 30, 2015 file photo. REUTERS/Oleksandr Klymenko

KIEV (Reuters) - Three Ukrainian servicemen have been killed and seven wounded in fighting with pro-Russian separatists in the past 24 hours, the Ukrainian military said on Tuesday, reporting the highest daily casualty toll since mid-November.

A year-old ceasefire deal has failed to stop violence in Ukraine’s separatist eastern territories, and international monitors have voiced concern over increased shelling in recent weeks.

“Yesterday the situation on the front line escalated. In general, every third enemy attack is from a heavy weapon or mortar banned under the Minsk (ceasefire) agreement,” military spokesman Oleksandr Motuzyanyk said in a daily televised briefing.

He said the fiercest fighting had taken place on the front line near the village of Zaitseve, about 30 miles (48 km) north of the rebel-controlled city of Donetsk.

The casualties reported by Motuzyanyk were the highest losses for the Ukrainian army since five servicemen were killed on Nov. 14, according to Reuters calculations based on military data.

This month, the head of the Organization for Security and Cooperation in Europe (OSCE), which monitors the implementation of the ceasefire, said he was deeply concerned about signs the conflict was escalating despite the peace agreement.

Meanwhile separatist rebels accuse government troops of violating the ceasefire on a daily basis. On Tuesday, separatist officials said shelling from the Ukrainian government side had hit Zaitseve as well as western suburbs of Donetsk.

Over 9,000 soldiers and civilians have been killed since the conflict began in April 2014, when pro-Russian separatists rose up after Moscow’s seizure of Ukraine’s Crimea region following the ousting of Kiev’s pro-Russian president by mass protests.