Unocoin has announced logins to its exchange will “resume shortly” after an apparent attack saw unauthorized transactions occur on user accounts. In a Monday update to users both on Twitter and its blog, the Indian exchange confirmed it would “refund” any missing coins to users.

At present, traders are unable to log in to accounts, a precaution taken by Unocoin after staff noticed the suspicious activity Sunday.

“We are now working on canceling the pending transactions to users. Unocoin has taken the responsibility to refund the few transactions that happened to get processed,” CEO and co-founder Sathvik Vishwanath writes in the blog post.

Little is known about the circumstances under which the transactions occurred, with Unocoin making no suggestion its security infrastructure remains vulnerable.

“At a moment’s notice, we looked into the matter and stopped all pending transactions and blocked access to our website. We have investigated and this does not a look to be a server compromise.” Vishwanath continued.

The episode follows more teething problems for the exchange late in June, when a further shutdown resulted in data servers being moved to a “more secure” location.