Boris Johnson should not be Foreign Secretary if he cannot be trusted to go to Moscow for talks over Syria, critics claimed after he pulled out of a meeting with his Russian counterpart.

Mr Johnson cancelled the trip following discussions with the United States but the move is a "gross miscalculation" looks “daft” and has landed him in “deep political trouble”, it has been claimed.

US secretary of state Rex Tillerson will go ahead with a planned trip to Moscow to deliver a “clear and co-ordinated” message to the Kremlin over its support for Bashar Assad's Syrian regime.

But the move makes the Foreign Secretary look like “some sort of mini-me” who cannot be trusted to hold his own talks with Russian foreign minister Sergey Lavrov, Alex Salmond said.

The SNP's foreign affairs spokesman told BBC1's Andrew Marr Show: “Boris Johnson just looks daft.

“What is the argument for not going ahead with a visit? Rex Tillerson is going on Wednesday so it can't be that we have moved to a Cold War position of no talking whatsoever.

“The idea the Foreign Secretary can't be trusted because he might pursue his own line or have an independent thought or crossover what the Americans are going to say just makes him look like some sort of mini-me to the United States of America.

“That's not a position any Foreign Secretary would want to be in.”

“Boris Johnson looks in deep political trouble this morning,” he added.

In pictures: US missile strike against Syria Show all 7 1 /7 In pictures: US missile strike against Syria In pictures: US missile strike against Syria The guided-missile destroyer USS Porter (DDG 78) launches a tomahawk land attack missile in the Mediterranean Sea AP In pictures: US missile strike against Syria The United States military launched at least 50 tomahawk cruise missiles at al-Shayrat military airfield near Homs, Syria, in response to the Syrian military's alleged use of chemical weapons in an airstrike in a rebel held area in Idlib province EPA In pictures: US missile strike against Syria Shayrat airfield in Syria Getty Images In pictures: US missile strike against Syria US Navy guided-missile destroyer USS Ross (DDG 71) fires a tomahawk land attack missile in Mediterranean Sea Reuters In pictures: US missile strike against Syria US Navy guided-missile destroyer USS Ross (DDG 71) fires a tomahawk land attack missile in Mediterranean Sea Reuters In pictures: US missile strike against Syria President Donald Trump speaks at Mar-a-Lago in Palm Beach, Fla., after the US fired a barrage of cruise missiles into Syria in retaliation for this week's gruesome chemical weapons attack against civilians AP In pictures: US missile strike against Syria Syria's President Bashar al-Assad Reuters

Liberal Democrat former leader Lord Campbell of Pittenweem said pulling out of the talks had been a “gross miscalculation” and was “frankly inexplicable”.

He told BBC Radio 4's Westminster Hour: “I doubt very much Mr Johnson had the authority to make that decision himself.

“It must have been a decision made at the highest level in government, doubtless with the Prime Minister and frankly I find it inexplicable.

“If your argument is that the solution to the issues in Syria is to be a political settlement then why avoid going to talk to one of the parties which will be an essential feature in any political settlement, namely Russia because of its close relationship with President Assad.

“I simply cannot understand why the Government took this position and in my view, candidly, I regard it as a gross miscalculation.”

“The fact of the matter is if Mr Johnson couldn't be trusted to go to Moscow, then he should not be the Foreign Secretary of the United Kingdom,” he added.

Russia has consistently denied that Syrian forces used chemical weapons, insisting the incident at Khan Sheikhoun was caused by a hit on a rebel chemical weapons plant, a claim dismissed by the West.

Russia's embassy in London tweeted: “It is deplorable that BorisJohnson found himself unfit to stand Western ground on Syria in bilateral talks with Sergey Lavrov.”

A Government source accused Mr Johnson's critics, including Lib Dem leader Tim Farron, of playing politics.

“It's a shame that some like Farron, Salmond and McDonnell put polls and politics above sorting out a civil war, it's very sad and shows how desperate they are,” they said.