The head of Russia's space agency is to step down after seven years in the job, a deputy prime minister announced Wednesday, after a string of problems and launch delays angered top officials.

Deputy Prime Minister Sergei Ivanov said that Roskosmos head Anatoly Perminov would be quitting as he had reached the maximum age of 65 allowed for state officials, and implied the change would come this month.

"Anatoly Nikolayevich Perminov is 65. According to Russian law, no state official can work once he is over this age," Russian news agencies quoted Ivanov as saying on a visit to Washington.

"Whether it is April 15, April 20 or April 30, I don't see any big difference," said Ivanov, adding that in any eventuality NASA administrator Charles Bolden will have a counterpart to meet when he visits Russia next week.

Despite the assurances that the change is due to Permonov's age, the news of his departure comes at an odd time just as Russia prepares to fete on April 12 the half century since Yuri Gagarin became the first man in space.

But it comes on the heels of one of the most embarrassing failures in the Russian space programme in recent times -- the failed launch in December of three navigation satellites that crashed into the ocean off Hawaii.

Russia's latest manned launch for the International Space Station just ahead of the Gagarin anniversary was also delayed from its planned lift-off date of March 30 due to a technical problem.

The Soyuz capsule -- adorned with a picture of Gagarin -- went into orbit early Tuesday but the RIA Novosti news agency said the delay caused major inconvenience as top officials had planned to attend the March 30 lift-off.

The delay was the "last straw for the country's leadership," the state agency quoted a source as saying, adding that Perminov could be shown the door even before April 12.

In a defiant statement posted on the agency's website later in the day, Perminov said it was up to the country's leadership to decide his fate.

Perminov said he was scheduled to meet his US counterpart Bolden on April 15, noting that the meeting's agenda had been agreed upon.

He added that some 40 heads of foreign space agencies will participate in the upcoming events to celebrate Gagarin's flight.