* Physical contract bid/offer spreads increase
* Tensions between Russia and Ukraine rise (Updates throughout)
LONDON, April 7 (Reuters) - European physical coal prices gained in late afternoon trade on Monday, tracking other energy markets on a revival of concerns about a possible Russian gas supply cut to Ukraine.
Cargoes for delivery in May to the ports of Amsterdam, Rotterdam and Antwerp (ARA) had a bid/offer spread of $77.00/$77.45, a broker said, compared to Friday's settlement price of $77.10 a tonne.
He put the bid/offer spread for the June contract at $76.00/$77.50 a tonne, after it last traded at $76.00 on March 25.
The API2 2015 coal futures contract drew bids of $80.60 a tonne, above Friday's settlement price of below $80.00.
Other energy markets gained ground on Monday afternoon on fears Russia could take over eastern Ukraine.
British gas for next-day delivery rose 5 percent to 51 pence per therm, while the benchmark contract for year-ahead baseload German power gained over 1 percent to 34.15 euros per megawatt-hour.
Pro-Russia activists occupying a regional government building in Donetsk, in eastern Ukraine, proclaimed the creation of a separatist Donetsk republic, prompting Ukraine's interim president to say Moscow had entered a "second stage" of operations aimed at breaking up Ukraine.
Also on Monday, the U.S. ambassador to the Organisation for Security and Cooperation in Europe said Russia had amassed tens of thousands of troops near the border with Ukraine, calling on Moscow to take steps to de-escalate the situation.
Meanwhile, Britain's National Grid said on Monday utilities were likely to burn more coal than gas in Britain this summer due to low demand for gas and low coal and carbon prices. (Reporting by Nina Chestney; Editing by David Evans and Dale Hudson)