US Senators have urged the Obama administration to send weapons to eastern Ukraine and help the country fight what they have called a "Russian invasion".

Robert Menendez, the head of the Senate Foreign Relations Committee said that Russian President Vladimir Putin must face the consequences of his "aggression", while Senator John McCain echoed similar voice by saying: "This is not an incursion. This is an invasion," the BBC notes.

"We should provide the Ukrainians with the type of defensive weapons that will impose a cost upon Putin for further aggression," Menendez, who is a Democrat, said while speaking to CNN.

"This is no longer the question of some rebel separatists; this is a direct invasion by Russia. And we must recognize it as that. When I read the headlines back at home that suggests rebels are advancing in different parts of eastern Ukraine it's not rebels it's Russian soldiers."

"Russia violated the international order that we had invited it to since the Cold War, a whole effort was to get Russia and other countries to observe that. You don't solve disputes by invading another country, taking over their territory, and annexing them. Russia has violated that," he added.

This comes as Putin on Sunday called for a dialogue between pro-Russian rebels and the Kiev government and suggested "statehood" for the eastern regions now controlled by separatists.

"Substantive, meaningful talks, concerning not only technical issues but also relating to the issues of the society's political organisation and statehood in south-eastern Ukraine, should begin immediately... to protect legitimate interests of people living there," he said in a television interview.

The new idea – if Putin indeed meant it – could raise the stakes considerably in the nearly 10-month-old Ukrainian crisis that has invited a surge of western sanctions against Moscow's alleged support for the separatists.

Meanwhile, the conflict seems to be spiralling its way into a major cold-war-type divergence with US senators suggesting that sending US weapons to the Ukrainian army could "very well be on the table right now," according to Menendez.

Calling for "Strong sections", Senator McCain also said Ukraine must be supplied with weapons.

Speaking to CBS's 'Face the Nation', he said Putin was "an old KGB colonel who wants to restore the Russian empire."

"Give them the weapons they need. Give them the wherewithal they need. Give them the ability to fight," he asserted.