Russian President Vladimir Putin says Moscow-Washington relations have worsened since US President Donald Trump took office in January.

"You can say that the level of trust on a working level, especially on the military side, has not improved but most likely worsened (under Trump)," Putin said in an interview published on Wednesday.

Touching on last week’s suspected chemical attack in Syria, which Western countries blamed on the Syrian government, Putin said the explosion was either due to the Syrian air force bombing on a militant chemical arms depot or the militants' ploy to discredit Syrian President Bashar al-Assad.

Over 80 people died in the purported gas attack in the town of Khan Shaykhun in Syria’s Idlib province on April 4.

Using the incident as a pretext, US warships in the eastern Mediterranean launched a barrage of 59 Tomahawk missiles against Shayrat airbase in Syria’s Homs province on April 7. Washington claimed that the airbase was the origin of the alleged chemical attack.

Elsewhere in his remarks, the Russian president rejected the accusations that Damascus was behind the Khan Shaykhun incident and slammed the US bombing as "a violation of international law."

The suspected chemical attack "has to be thoroughly investigated to give a final answer. There is no other way out. And this is what we are proposing to do," he stressed.

Putin said on Tuesday that the US missile strike over the alleged gas attack was reminiscent of a plot hatched in the run-up to the 2003 invasion of Iraq.

Earlier on Wednesday, Russian Foreign Minister Sergei Lavrov held a meeting with US Secretary of State Rex Tillerson in Moscow.

The top Russian diplomat denounced the US missile strike on Syria as “illegal” and accused Washington of carrying out “extremely worrying actions.”

He also warned the US against staging a repeat of its missile attack against Syria.

West's calls on Moscow to distance itself from Assad 'absurd'

Separately on Wednesday, Kremlin spokesman Dmitry Peskov told a press conference that Western powers' calls on Russia to stop backing President Assad amount to giving terrorists a free hand.

"That’s why posing a question that Russia should stop supporting Assad and therefore stop backing his efforts in the fight against Daesh sounds quite absurd… This is probably relevant to the calls to stop assistance (to the Syrian government), and plays into the hands of terrorists so that they could continue their advance against the legitimate authorities of Syria," Peskov said

Assad is a legitimate leader from the viewpoint of international law and is also the commander-in-chief of Syria’s armed forces battling international terrorists, he added.

The Russian official further dismissed as "information mess" the latest US accusations that Moscow tried to cover up Damascus' complicity in the chemical incident.