* Olympiakos say supporters did not display a racist banner
* Appeal against partial ground closure for Man United match
* Zenit accept UEFA sanctions for fans' racist behaviour (Adds Zenit accepting sanctions)
By Graham Wood
ATHENS, Dec 18 (Reuters) - Olympiakos Piraeus have appealed against the partial closure of their ground for February's Champions League tie with Manchester United arguing that UEFA's sanctions were harsh as there was no racist behaviour by the fans.
European soccer's governing body said on Tuesday that the sanctions were imposed for "the racist conduct of supporters, insufficient organisation, the setting-off of fireworks and the use of a laser" in the Group C match with Anderlecht on Dec. 10.
UEFA has ordered the Greek champions to close the north stand lower tier at the Georgios Karaiskakis Stadium, where their Gate 7 ultras gather, for the last 16, first-leg clash against United on Feb. 25.
UEFA also fined Olympiakos 30,000 euros ($41,200).
However, Olympiakos press spokesman Kostas Karapapas wrote on his Facebook account on Wednesday: "The punishment is because of one particular banner which as soon as it was seen was taken down and that is why it is harsh to say the least.
"There was no racist slogan or racist banner, and no racist chanting or songs were heard during the match with Anderlecht," he added.
Greek media reported that the banner depicted a man who had been decapitated.
"The punishment from UEFA is a first level decision and we have submitted an appeal to try to ensure that our stadium is full for the match against Manchester United," added Karapapas.
"It is a shame that some people don't want to see the Gate 7 area full for the match."
Olympiakos missed two penalties but still won 3-1 against Anderlecht, who finished with eight men, to qualify for the knockout phase of the Champions League as Group C runners-up above Benfica by virtue of a better head-to-head record.
Zenit St Petersburg were also sanctioned by UEFA for incidents during a 4-1 loss at Austria Vienna in their final group game but the club said on Wednesday they would not appeal.
The Russian league leaders must close four sections of the Petrovsky Stadium, which usually house their ultras, against Borussia Dortmund in their last 16 first-leg tie on Feb. 25.
UEFA said Zenit had been punished for "the racist behaviour of fans - namely the displaying of a banner - the setting-off and throwing of fireworks and crowd disturbances". The club were also fined 40,000 euros ($54,900) for the ugly scenes.
"We accept the sanction and we'll not appeal against it as it would be inappropriate," it said in a statement on Wednesday.
Last week, Zenit condemned violence by their fans, saying the trouble-makers led to the team's poor performance in Vienna while Italian coach Luciano Spalletti described the hooligans as "enemies" and said they should stay away from football grounds.
Macedonian referee Aleksandar Stavrev interrupted the match in Austria for a few minutes in the first half after a number of flares were thrown from the Zenit fans into the crowd below.
Big-spending Zenit, owned by Russian energy giant Gazprom , became the first team to qualify for the Champions League knockout stage with only six points from six matches when they finished runners-up to Atletico Madrid in Group G.
($1 = 0.7283 euros) (Reporting by Graham Wood, additional reporting by Angel Krasimirov; editing by Ken Ferris)