Arsene Wenger: Olivier Giroud's great form means Arsenal do not need to sign Karim Benzema

Arsenal manager Arsene Wenger believes Olivier Giroud's quality means the club do not need to sign Karim Benzema.

Giroud scored a hat-trick against Olympiakos on Wednesday night as the Gunners secured their spot in the Champions League knock-out stages in stunning fashion, defeating Olympiakos 3-0 in Greece.

It was the culmination of a fantastic run of form from the France striker, who has now scored 10 goals in his last 12 appearances.

Despite often being criticised as a forward who is not clinical enough to help Arsenal sustain a title challenge, Giroud has taken on the goalscoring burden as both Theo Walcott and Alexis Sanchez have been sidelined with injury this season.

And Wenger, whose side travel to the Premier League's bottom side Aston Villa on Sunday, reckons the 29-year-old is just as good as those strikers who are considered to be the deadliest in world football.

"I think he's in that league because he plays for one of the best clubs in Europe and he scores goals," Wenger said.

"If you look at the number of games and the number of goals, you have to give him credit.

"He's not only a goalscorer, he's a guy who puts work in for the team. I think he's among the best strikers in Europe.

"I believe recently he has come back with an improved game and with his finishing. Wednesday was one of his best performances on all fronts."

Giroud had to be patient earlier in the campaign as Walcott was preferred as Wenger's main striker - but he has since taken his opportunity to make the position his own.

The victory in Greece was the first time this season the pair had started a game together and, while Wenger plans to rotate them in order to give either one a break, he insists the duo can be deployed at the same time.

"He (Giroud) is not exhausted in December because a striker is a bit of a more demanding job and he had a breather and came in and out," he said.

"I think I will have to do that again because it is so demanding now and he has a game that demands a lot of energy, that sometimes you need a breather in that squad.

"They can play together well, what I did on Wednesday night, so in some games I will play them together. It depends on the global balance of the team, it is a bit more different when Alexis is there as well."

Wenger has long been linked with Giroud's international colleague Benzema - who will be missing from the national team for the forseeable future after French Football Federation president Noel Le Graet said he was "no longer selectable" due to an ongoing blackmail case.

The Real Madrid man is facing provisional charges of conspiracy to blackmail and was interviewed by police in France on November 5 over his involvement in an alleged attempt to extort money over a sex-tape reportedly showing Les Bleus team-mate Mathieu Valbuena and his partner.

Wenger believes it is right to leave Benzema out and dismissed a move for the 27-year-old.

"We just said that Olivier Giroud is a great striker, so behind that we cannot buy Karim Benzema," he said.

"I think it is a legal case and as long as it has not been judged, you have to wait for the judgement. At the moment he cannot play because he is under investigation and as long as he is not cleared, he should not play."

Wenger also refuted newspaper claims he was set to launch a January move for Southampton midfielder Victor Wanyama, despite the fact he currently has four players in that position out injured - saying: "I rate the player but we are not on the case."Sunday's clash at Villa Park will come too early for those four midfielders - Mikel Arteta, Santi Cazorla, Jack Wilshere and Francis Coquelin.

There is also no chance of Sanchez returning from his hamstring issue so Walcott and Giroud are likely to start again.

Additional reporting by PA...