MOSCOW (REUTERS, AFP) - The Kremlin on Thursday (March 22) warned against talking about a breakthrough in Russia-United States relations despite a possible meeting between Russian President Vladimir Putin and US President Donald Trump.

"Let's not talk about any breakthroughs; firstly we should talk about as a starting point getting a dialogue going. We have a long way to go before any breakthrough," Kremlin spokesman Dmitry Peskov told reporters on a daily conference call.

Mr Trump on Tuesday congratulated Mr Putin on his re-election and said they would likely meet soon as relations between the two countries grow more strained over allegations of Russian meddling in the US electoral system.

On Thursday, the Kremlin also slammed British Foreign Secretary Boris Johnson, who said that President Putin is seeking to exploit Russia's World Cup in the way Adolf Hitler had used the 1936 Berlin Olympics.

"This is a completely disgusting statement. This is beneath the foreign minister of any country. Of course it is offensive and unacceptable," Mr Peskov said.

The previous day, Mr Johnson agreed with a fellow British MP who had suggested that "Putin is going to use it in the way Hitler used the 1936 Olympics", as a propaganda exercise.

"I think the comparison with 1936 is certainly right," the minister replied, envisaging Mr Putin "glorying in this sporting event".

The comments came amid an escalating war of words between Russia and Britain over the poisoning of a Russian former double agent on British soil this month. Moscow denies involvement in the case.

Mr Johnson also called for Russian guarantees over the safety of England fans at the World Cup.