New Delhi | The Department of Space has issued a memorandum to major ISRO centres for tightening the rules governing the resignation and voluntary retirement of scientists and engineers working in critical missions of national importance such as the Gaganyaan Mission.

The memorandum, issued on Tuesday, directed these centres not to routinely accept resignation or voluntary retirement requests from Group 'A' scientific and technical personnel.

This development comes as reports have emerged that more than 100 ISRO personnel have quit the space agency across various centres in the country.

"Of late, it is noticed that there has been spate of requests for voluntary retirement and resignation from Group 'A' Scientific/ Technical personnel of ISRO including those associated with the prestigious Gaganyaan and other important missions/ projects severely impacting the implementation of projects of national importance," said the memorandum.

"In view of this, it has been decided that voluntary retirement and resignation requests from Scientific & Technical personnel associated with the Gaganyaan and other important Mission/ Projects may not be accepted as a matter of routine," it added.

Such requests from scientists and technical personnel, even at or below the rank of scientist and engineer, must now be sent to the Department of Space with "clear recommendations" from their directors for a final decision, according to the memorandum.

The ISRO centres which have received the memorandum include UR Rao Satellite Centre (URSC) and the Vikram Sarabhai Space Centre (VSSC).