Bitcoin transactions at one of the world's largest Bitcoin exchanges were interrupted late Thursday night by a "stronger than average" DDos attack that affected the Bitcoin rate of exchange. No word on who was behind the latest round of cyber attacks.

The Japanese company, which is rated as the largest exchange for bitcoins, was hit by a DDoS attack that was "stronger than the average," the exchange's support team said. Such attacks aim to overwhelm systems by sending an overload of requests to websites.

Bitcoins use a distributed, peer-to-peer cryptographic system to verify transactions. A number of websites including blogging platform WordPress and social news site Reddit have started accepting payments by bitcoins. Expense reports management software firm Expensify said this week that it added bitcoin as a reimbursement option for expense reports. "We see Bitcoin as more than just a gimmick," it said in a blog post.

Payments startup Dwolla also reported a DDoS on its systems on Wednesday from which it was still recovering. The system is also used to trade in bitcoins, and Mt. Gox said in a support message on Friday that it was unable to process deposits and withdrawals through Dwolla.

The attack on Mt. Gox comes at a time when the virtual currency has seen a surge in value and popularity, leading to speculation that it has emerged as a strong hedge against the economic crisis in Cyprus.