The former Sports Minister and Russian Football Union head was speaking during a visit to Saransk to inspect progress at the 44,000 capacity Mordovia Arena.

He insists there are no excuses despite the economic problems currently plaguing the host nation.

"We are all well aware of the difficulties and problems in our economy," Mutko told the TASS news agency.

"We did an outstanding job having accomplished a great deal in terms of our preparations for the World Cup, however there is still much work to be done ahead of us.

"The World Cup is an extremely complicated project. 

"We must do our utmost to complete the main stage of the preparation works by the end of the year."

Mutko, who has been barred from standing for re-election to FIFA's ruling Council this year after failing an eligibility check, believes construction challenges pose more of a threat than financial issues.

"We still have the facilities, which raise concerns and we need to turn our attention in this direction," he added.

"I am sure that we will be capable of taking care of the financial aspect, but the aspect of the operational services must be attended to.

"Problems emerge each time when we encounter construction postponements and financing delays.

"Everything must be done to comply with the main construction schedules."

Russian markets have fallen again in recent weeks as speculation grew over the likelihood of fresh sanctions being imposed by nations including the United States.

Pavel Kolobkov, Mutko's replacement as Sports Minister, has also vowed to step-up security following a terrorist attack earlier this month in Saint Petersburg.

A device hidden in a briefcase triggered an explosion on the metro line on April 3, killing 14 and leaving a further 45 injured.

Saransk is one of 11 cities due to host matches during the showpiece event.

Construction at the Mordovia Arena began in 2010 but is still not yet completely finished. 

Work there and at other venues is considered fairly minor, however.

The FIFA World Cup is scheduled for June 14 until July 15 in 2018.

But Moscow, Sochi, Kazan and Saint Petersburg are all due to host matches this year at the Confederations Cup, scheduled for June 17 to July 2.

The first match is due to take place at the new Krestovsky Stadium in Saint Petersburg.

FIFA have now approved the venue amid several cost and construction-timetable overruns.

The Stadium has received criticism for a rising budget that spiralled to a current projection of around ₽41 billion (£571 million/$714 million/€677 million).