The continued interest in alternative cryptocurrencies to bitcoin is clear to see Swedish-based KnCMiner selling $2 million (£1.2m)worth of scrypt-based mining rigs in just four hours.

The Titan is the company's first scrypt-based mining rig and costs $10,000, meaning the company sold 200 units in the first four hours it was available to pre-order on the website.

KnCMiner saying the Titan rigs will be shipping in the second or third quarter of 2014. The company said it would make 2,500 units in the initial run but with interest in scrypt-based coins growing, KnCMiner is likely to sell out of the devices.

The company also sells the Neptune bitcoin mining rig which also costs $10,000, and in December the company revealed it had sold $8 million worth of Neptune hardware in just 24 hours, claiming the Neptune rig would be able to mine 2.1 bitcoins a day - then worth over $2,000 but now worth around $1,300.

"The scrypt mining market has grown over the last six months and we have been watching it very closely. The time is now right for the launch of our new offering," the company said on its website.

Bitcoin uses the SHA256 cryptographic hash function but most of the newer cryptocurrencies use the scrypt function, meaning that you can still use your GPU and CPU to mine the coins - something which is no longer really possible in bitcoin mining.

Popular scrypt-based alt-coins include litecoin (the world's second most valuable cryptocurrency) and dogecoin, the meme-based cryptocurrency.

Until recently there no one was selling specially-built mining rigs for scrypt-based alt-coins as the return on investment on such coins was not at the level where people were willing to invest a lot of money in hardware like Titan.