The earthquakes left around 1,500 people injured, the Channel News Asia broadcaster said, adding that hundreds of thousands were left homeless due to the disaster.
On Monday, the agency's spokesman said that the death toll amounted to 506 people.
On Sunday, Lombok was hit by a 6.9-magnitude earthquake. The quake's epicenter was located at the depth of 10 kilometers (6.2 miles).
Earlier in August, the island was struck by a 7.0-magnitude quake, reportedly claiming the lives of 436 people.
According to the country's Tourism Minister Arif Yahya, Lombok may lose around 100,000 tourists in 2018 over the earthquakes. He said that Bali had lost around 1 million tourists over six months following the Mount Agung eruption in November 2017.
"I project that the loss of tourists in Lombok will follow the same pattern as in Bali, with a ratio of one to six. Lombok will start recovering in early September, while the recovery process will take six months," Yahya said, as quoted by the Jakarta Post newspaper.
The minister claims that while Bali receives around 6 million tourists every year, around 1 million tourists come to Lombok annually.