BRUSSELS: The EU said Friday that Russian President Vladimir Putin had written to Brussels demanding changes to a landmark EU-Ukraine accord, but it ruled out reopening the deal without Kiev’s consent.

Putin’s letter to European Commission chief Jose Manuel Barroso reportedly threatened retaliatory measures if the EU and Ukraine do not stick to their agreement with Moscow to delay the implementation of the deal until 2016.

The Ukrainian and European parliaments last week both ratified the association agreement, the rejection of which by then-president Viktor Yanukovych last year triggered the political crisis in the former Soviet state.

European Commission spokeswoman Pia Ahrenkilde Hansen confirmed that Barroso had received a letter from Putin about the deal and said Brussels “will of course decide on the best way to respond.”

But she pointed out that the controversial pact was a “bilateral agreement” between Kiev and Brussels.

“If there are any changes they have to be agreed between the EU and Ukraine,” Hansen told a press briefing.

“We are not seeking any changes to the agreement, Ukraine is free and sovereign to make choices in its interests.”

The Association Accord, which includes a wide-ranging Free Trade Agreement, is at the heart of the bitter stand-off between the EU and Russia over the future of its Soviet-era satellite.

Moscow has repeatedly charged that the tie-up damages its legitimate interests and its economy.