The CEO of Kingfisher Airlines Ltd, grounded since the start of the month, urged striking employees to return to work as the carrier scrambled to find solutions to its cash flow problems.

Shares in the carrier fell 5 percent, their daily limit, for the eighth straight session on Wednesday as investors lose hope that the airline controlled by liquor baron Vijay Mallya will get a lifeline from a foreign airline or another saviour.

The carrier has until the end of next week to explain to the government why it should not be shut.

"Without all of you, without exception, coming back to work, we will have no way forward," CEO Sanjay Aggarwal said in a letter to employees on Tuesday.

"We have been working relentlessly to try and rectify this situation, and that too against all odds," Aggarwal wrote in the letter seen by Reuters.

Kingfisher has so far failed in its long-running search for an investor and is $2.5 billion in debt

by one estimate. The carrier has grounded its fleet since October 1 after an employee protest turned violent.

Staff, who have not been paid for seven months, held protest marches late last week after what police said was the suicide of a Delhi-based employee's wife worried about her family’s precarious finances.

Meetings last week between the carrier and pilots and engineers demanding their back pay failed to reach an agreement.

Late on Friday, India's aviation regulator sent a "show-cause" notice to Kingfisher asking why its license to fly should not be cancelled after failing to provide a "safe, efficient and reliable service."

The airline was given 15 days to respond.

The regulator has also asked Kingfisher to stop selling tickets until its concerns are resolved.

"We are aware it is a big ask, but no potential investor will put his money in an airline that is not operational. Neither will our esteemed guests come back to us unless we commence operations soon," Aggarwal wrote to staff.