Diego Costa
Costa is 'fine' according to his national team boss.Getty

Spain manager Vicente del Bosque has waved away Jose Mourinho's concerns about Chelsea star Diego Costa's fitness, insisting the striker is 'fine' to start for his national team next week.

Costa, 25, has enjoyed an explosive start to life at Stamford Bridge having struck eight goals in his first six appearances for the Blues despite concerns over a persistent hamstring problem.

After being named in the Spain squad for upcoming European Championship qualifiers against Slovakia on 9 October and Luxembourg on 12 October, Costa's club manager Mourinho again reiterated his doubts over the player's ability to feature in three games a week on a consistent basis.

The Chelsea boss has previously urged Spain to rest the striker, telling reporters on Friday he will not take him out of his starting XI ahead of Chelsea's visit to Arsenal on Sunday. This will be Costa's third game in eight days.

But Del Bosque has risked the wrath of Mourinho but brushing off his concerns, insisting his team doctors are fully aware of Costa's condition.

"We believe Costa is fine," Del Bosque told a press conference. "He is playing every game for Chelsea and if we felt he wasn't in good enough condition we wouldn't force it. That is why we have our doctors. They are the ones who tell us if he is fine or not."

On Friday Mourinho insisted Costa's fitness after the final whistle has blown against Arsene Wenger's side on Sunday is no longer his problem for the duration of the international break.

"My reaction [to the news that he is in the Spanish squad] is no reaction. I don't know [when Costa is going to be fully fit]. He will play against Arsenal," Mourinho told reporters.

"I think it's too much [for him to play three games]. But he will do that because I'm not going to save him to be in perfect condition for the national team.

"If he has a problem playing against Arsenal, he has a problem playing for Chelsea. What happens after that in the 15 days is not for me, it's not my responsibility.

"I will have the consequences of that, like all the other coaches who have players in national teams."