Emaar Malls PJSC, the shopping-center unit of Dubai’s biggest publicly traded property developer, made a bid for online retailer Souq.com, seeking to challenge an existing offer from Amazon.com Inc., according to people familiar with the matter.

The unit of Emaar Properties PJSC offered about $800 million for Souq.com this week, which includes a convertible deposit of $500 million, one of the people said, asking not to be identified as the information is private. Amazon has an exclusivity clause in its buyout talks for Souq.com, the person said. No final agreement has been reached with any of the parties, the people said.

A spokesman for Emaar declined to comment. A representative for Souq.com couldn’t immediately be reached for comment. The bid was previously reported by Arabian Business.

Amazon restarted talks to acquire Souq.com in a deal valued at as much as $650 million after walking away earlier this year, people familiar with the matter said earlier this month. Souq.com was valued at $1 billion in its last funding round, people with knowledge of the matter said in April 2015. The retailer raised $275 million, making it the most valuable internet company in the Middle East, according to Standard Chartered Plc, which had invested in the company.

Dubai-based Souq.com’s existing investors include Tiger Global Management and South Africa’s Naspers Ltd. The company hired Goldman Sachs Group Inc. to find buyers for a stake last year, people said at the time.