Kazakhstan's environment minister said Thursday he is "dissatisfied" with the cleanup effort following the crash last month of a Russian space rocket.

A Russian Proton-M rocket carrying three satellites veered off course seconds after its launch from Kazakhstan's Baikonur space center on July 2, crashing in a cloud of toxic heptyl, amyl and kerosene fuels.

Between 500 and 600 tons of heptyl was reportedly on board the craft at the time of the crash, RIA Novosti reported.

Kazakh Environment Minister Nurlan Kapparov "expressed dissatisfaction over the results and the pace" of cleanup operations at the site of the crash, the ministry said in a statement.

Russia's Roscosmos space agency has asked for another 15 days to complete the cleanup, the ministry said.

A Roscosmos spokesman said the concentration of toxic substances in the soil had been reduced to a fraction of maximum permissible levels and that cleanup should be finished by the end of the month.

The Kazakh government has set up a commission to investigate the accident's aftermath, Kapparov said, and would conduct ongoing monitoring of the crash site.