LONDON • The United States has shared intelligence with its European allies that shows a build-up of Russian troops and artillery in preparation for a large-scale push into Ukraine from multiple sites if President Vladimir Putin so decided, according to people familiar with the conversations.

The intelligence, which includes maps, was conveyed to some Nato members in the past week amid US concerns over Mr Putin's possible intentions and an increasingly frantic diplomatic effort to deter him from any incursion, with European leaders engaging directly with the Russian leader.

The diplomacy is informed by an American assessment that Mr Putin could be weighing an invasion early next year as his troops again mass near the border. The information lays out a scenario where troops would cross into Ukraine from Crimea, Russia and via Belarus, with about 100 battalion tactical groups - comprising potentially some 100,000 soldiers - deployed.

Two of the sources said that about half that number of tactical groups were already in position and that any invasion would be backed up by air support.

The two sources said Moscow had also called up tens of thousands of reservists on a scale unprecedented in post-Soviet times.

They explained that the role of reservists in any conflict would be to secure territory in a later phase after the tactical battalions have paved the way.

Russia has not announced any major call-up of reservists.

Moscow on Sunday dismissed such suggestions as inflammatory and complained about what it says is increasing activity in the region by the Nato alliance.

Kremlin spokesman Dmitry Peskov said in comments broadcast on Sunday that "a provocation" in the area could not be ruled out, given all the US rhetoric.

"This hysteria is being artificially whipped up. We are being accused of some kind of unusual military activity on our territory by those who have brought in their armed forces from across the ocean. That is, the United States of America. It's not really logical or polite."

Mr Peskov suggested Ukraine was probably looking for a way to solve its own problems by force.

Russia annexed Ukraine's Crimean Peninsula in 2014 and Russian-backed separatists seized a swathe of eastern Ukraine that same year.

That triggered sweeping US and European sanctions, but the conflict has continued, killing about 14,000 people in east Ukraine.

The US has also shared intelligence about an exponential rise in disinformation targeting Kiev, and said Moscow has recruited agents to try to cause destabilisation inside Ukraine, one of the two sources told Bloomberg.

Mr Putin last week denied any intention to invade, but welcomed the alarm as evidence that his actions had got the attention of the US and its allies, which he accused of failing to take Russia's "red lines" over Ukraine seriously enough.

America and others are not saying a war is certain, or even that they know for sure Mr Putin is serious about one. The sources said it is likely he has not yet decided what to do.

US Secretary of State Antony Blinken said this month: "I can't speak to Russia's intentions. We don't know what they are."

A senior administration official said the US has, under President Joe Biden, demonstrated it is willing to use a number of tools to address harmful Russian actions and would continue to do so.

Mr Putin has a history of brinkmanship and prior build-ups on the border have come to naught.

But officials say the Russian leader is positioning to act if he wanted to, and they note that even as troops withdrew from an earlier escalation in April, they left equipment behind, making the fresh build-up faster and easier.

For Mr Putin, Ukraine is unfinished business after his annexation of Crimea. He sees Ukraine as part of Russia and bristles at its outreach with the West, especially its nascent military engagement with Nato, or the North Atlantic Treaty Organisation.

Ukraine's Foreign Minister Dmytro Kuleba, who travelled to Brussels in Belgium last week, told Ukraine television that an incursion was clearly an option for Moscow and that Kiev needed support from others to deter it.

BLOOMBERG, REUTERS