Story highlights Ukraine says eight soldiers have recently been killed

Russia says rebels are using banned weapons

(CNN) Fighting in eastern Ukraine between pro-Russian rebels and Ukrainian armed forces is escalating, officials have warned.

A higher number of ceasefire violations were reported between Sunday and Monday evenings, compared with the previous 24 hours, the Organization for Security and Co-operation in Europe Special Monitoring Mission to Ukraine said Monday.

The Ukrainian Foreign Ministry said eight Ukrainian soldiers were killed in the Donbass region in two days.

"Russian occupation forces carried out massive attacks across the contact line using all available weapons, including (artillery, mortars and tanks) -- all prohibited by the Minsk agreements -- and small arms," the ministry said. At least 26 troops were wounded.

We urge the Ukrainian authorities to immediately put an end to the armed provocations in #Donbass https://t.co/x5DE1vKZEg pic.twitter.com/9KaoAQglyb — MFA Russia 🇷🇺 (@mfa_russia) January 31, 2017

The US State Department on Tuesday put out a statement saying: "The United States is deeply concerned with the recent spike in violence in eastern Ukraine around (the cities of) Avdiivka-Yasynuvata."

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