But soccer’s world governing body said his presence did not directly violate his ban from football activities.
Blatter, who led FIFA for 17 years, is serving a six-year ban from “all football activities” for unethical conduct, after FIFA was rocked by a global corruption scandal in 2015.
His appearance at the World Cup in Russia is potentially embarrassing for FIFA and its new head, Gianni Infantino, who has promised to draw a line under FIFA’s corruption problems and clean up the organisation.
TASS news agency quoted Alexei Sorokin, head of the Russia-2018 organising committee, as saying he had seen Infantino and Blatter at Moscow’s Luzhniki Stadium watching Portugal’s 1-0 win over Morocco.
“Today I saw Infantino and Blatter at the stadium, it’s true,” TASS quoted Sorokin as saying.
In an interview with Britain’s Channel 4 News, Blatter said he had been invited to the World Cup by the Russian organising committee, and FIFA should respect his right to be at the tournament.
“I am not in football activities. I am a personal guest here today,” he said.
“It should not be an embarrassment to FIFA. If FIFA would have a little bit of respect, knowing that I have an official invitation to come here.”
FIFA said that Blatter attending Moscow match did not directly constitute a breach of his ban.
Blatter told Reuters in March he had been invited to attend the World Cup by President Vladimir Putin, with whom he has a long-standing close relationship.
A spokesman for Blatter said he was scheduled to meet with the Russian leader while in Moscow.
Kremlin spokesman Dmitry Peskov told reporters on Wednesday Blatter was visiting Russia in a non-official capacity, and Blatter later said his meeting with Putin had not yet been confirmed.
“Any meetings that could be held are being realised in the framework of his private visit and are not official,” Peskov said when asked if Blatter has met or would meet Putin.
Blatter’s ban was imposed shortly after the Swiss attorney general’s office began criminal proceedings against him, on suspicion of criminal mismanagement and misappropriation.
No charges have yet been brought and Blatter has repeatedly denied any wrongdoing.
The 82-year-old struck a defiant tone in Moscow, describing the criminal probe as “an attack on FIFA” and saying he was still president of the organisation.
“I was suspended, I’m still a suspended president. I’m still president, but suspended,” he told Russian news channel RT.
“It was not an easy time for me, it’s still not the easiest time.”
Speaking in front of the Kremlin against a backdrop of football fans queuing to visit Moscow’s Red Square, Blatter said he had advocated Russia be chosen as the World Cup host in 2010.
“When I arrived yesterday, I saw it a little bit, it’s my World Cup. How I was received here, television, cameras, people photographs and so on,” he said.
When asked how he had been occupying his time since the ban, the former FIFA boss said he was grappling with how to solve the problem of political intervention in world football.
“Football should not be dominated by politics. Football should help, perhaps, to solve political problems,” he said.
“But in the past we have seen that there is political intervention for football.”