A spaceship designer who worked on Yury Gagarin's Vostok spaceship and was the last to shake his hand before liftoff, Oleg Ivanovsky, died on Thursday at 92, the Russian space agency said.

Ivanovsky was a senior designer at the facility codenamed OKB-1 which built the Vostok spaceship that blasted Gagarin into orbit in 1961.

"He participated directly in preparing the flight of the world's first cosmonaut," Roscosmos said in a statement.

"The last to shake the hand of the world's first cosmonaut before blastoff was Oleg Genrikhovich Ivanovsky. After that he closed the hatch of the ship," Roscosmos said, using his patronymic.

Photographs published by Roscosmos show Ivanovsky, a slight man in blue overalls over a shirt and tie, helping Gagarin climb the stairs up to the spaceship and get into his seat.

"I squeezed into the cabin. I hugged him, shook his hand and gave him a slap on the helmet before getting out. A moment later and the hatch swung closed onto its locks," Ivanovsky remembered in a 2007 interview with Rossiiskaya Gazeta daily.

A tense moment followed as the chief designer, Sergei Korolyov warned that there was a glitch: the hatch's locks were not registering as hermetically sealed.

Ivanovsky recalled he swiftly had to remove and replace the hatch, attached by 32 bolts, as Gagarin watched him in a mirror sewn onto his sleeve, while quietly whistling a song with the lyrics: "The motherland hears, the motherland knows..."

It turned out later that the hatch was in fact fine -- one of the light bulbs at mission control was simply faulty and flashed an error message by mistake, Ivanovsky said.

The engineers had a secret code they planned to use if Gagarin fell unconscious or started raving.

"Out of seven flights of Vostok ships before Gagarin's, only three were successful. And only two returned to Earth. So it was a big risk, of course," he recalled.

"But we did everything we could to make the flight safe according to the level of knowledge and the capabilities we then had."

Ivanovsky was born in Moscow and fought in World War II, taking part in the Victory Parade on Red Square.

After the war, he studied at Moscow Energy Institute. He began working as a senior engineer in spaceship construction in 1957 and later worked on the Soviet Union's unmanned lunar missions.

"He was an incredible person, a hero who lived his life in the name of science and to benefit the motherland," Roscosmos said in a statement.