Ukraine has decided to expel 13 Russian diplomats as a sign of solidarity with its British partners and trans-Atlantic allies and in coordination with European Union countries, Ukrainian President Petro Poroshenko has said.

"In reply to the cynical chemical attack in Salisbury, the United Kingdom, acting in a spirit of solidarity with our British partners and trans-Atlantic allies and in coordination with the EU countries, Ukraine has decided to expel 13 of the few remaining Russian diplomats from Ukrainian territory, considering that, as is well known, our diplomatic relations with Russia have de facto been frozen," Poroshenko said on Facebook on Monday.

Russia has once again manifested its disdain not only for sovereignty of independent states but also for the value of human life, he said. Ukraine feels this everyday in the occupied Crimea and in Donbas, the president added.

"Therefore, it is important as never before not to confine ourselves to symbolic gestures. The next step should be increasing the price Moscow has to pay for international crimes it has committed, including by elevating personal, financial, and economic sanctions. Our common response to the Kremlin should continue to be resolute and tough to prevent new human tragedies and ensure respect for international law," he said.