LONDON — International Olympic Committee president Thomas Bach said Monday that he had complete faith in President Vladimir Putin’s ability to deliver a “safe and secure” Winter Games in Sochi, after two suicide bomb attacks struck the southern Russian city of Volgograd.

“I have personally written to the President of the Russian Federation, Vladimir Putin, to express our condolences to the Russian people and our confidence in the Russian authorities to deliver safe and secure Games in Sochi,” he said. “I am certain that everything will be done to ensure the security of the athletes and all the participants of the Olympic Games.”

On Monday, Putin ordered a ramping up of security at transport hubs across Russia less than six weeks ahead of the Sochi Winter Olympics. He delivered a series of new measures to the country’s Anti-Terrorism Committee to “strengthen security Russia-wide and specifically in the Volgograd region.”

The first bomb attack on Sunday killed 17 people at a train station in Volgograd, which is a major transport hub some 400 miles north of the Black Sea resort of Sochi. The second attack in Volgograd, on a trolleybus on Monday, killed 14.

Volgograd, formerly called Stalingrad, has great symbolic significance for Russians as it was the site for a bloody battle against the invading Nazis in World War II. Fedor Bondarchuk’s film about the battle, “Stalingrad,” topped the Russian box office last year.

With the opening of the Winter Olympics just six weeks away, attention has focused on threats by terrorist groups to disrupt the Games. In a video message posted on Islamist sites in July, Doku Umarov, a rebel leader in the North Caucasus region, instructed followers to use “maximum force” to prevent the Games from going ahead.

“We can expect more such attacks,” Alexei Filatov, deputy head of the veterans’ association of Alfa, the elite anti-terrorism unit, told Euronews wire service. “The threat is greatest now because it is when terrorists can make the biggest impression. The security measures were beefed up long ago around Sochi, so terrorists will strike instead in these nearby cities like Volgograd.”

Andrei Soldatov, a security expert, told the Telegraph newspaper that an attack on the Games was in the cards. “I think it is best to be pessimistic in the current situation,” he said.

Bach condemned the attacks Monday: “This is a despicable attack on innocent people and the entire Olympic movement joins me in utterly condemning this cowardly act. Our thoughts are with the loved ones of the victims.

He added: “Sadly, terrorism is a global disease but it must never be allowed to triumph. The Olympic Games are about bringing people from all backgrounds and beliefs together to overcome our differences in a peaceful way.

“The many messages of support and solidarity from the international community make me confident that this message will also be delivered by the Olympic Winter Games in Sochi.”