US retail giant Wal-Mart is launching an unlimited subscription-based fast-shipping service, posing stiff competition to online retailer Amazon.

Technology news website, the Information, reported that the service, codenamed "Tahoe", will be similar to Amazon Prime, and is intended to boost Wal-Mart online business.

The service comes after a painful multi-year software overhaul for Wal-Mart's e-commerce business, the website noted. It was supposed to be launched in 2014, but was delayed several times due to technical and other issues.

The Information noted that the service will be available in the next few weeks or early summer. The company did not specify which markets would have access to the programme.

While Amazon charges $99 (£63.1, €87.8) per year for its service that offers fast shipping and discounts on an array of products, Wal-Mart's similar service would cost $50 per year.

Amazon Prime also provides customers with access to online streaming of music, movies and TV shows. The service has become one of the major contributors to Amazon's growth, as its members grew 50% in 2014.

At the end of 2014, Amazon Prime had 40 million members in the US, compared to an estimated 29 million at the end of the third quarter of 2014, according to data from Consumer Intelligence Research Partners.

Wal-Mart will begin the service on an invitation-only basis as of now, offering more than one million top-selling items on the company's website to customers in three days or less, according to company spokesman Ravi Jariwala. Wal-Mart offers more than seven million products on its website.

"Depending on customer feedback we will see how the program evolves," Jariwala said.

He added that the service would not offer features like free video and music streaming like Amazon.

"This is just one of many tests we have going on," he said.