British singer Adele regained the top spot on Monday on the weekly U.S. Billboard 200 chart, while R&B star Rihanna's latest record sold less than 500 copies after a million copies were given away for free, making them ineligible for Billboard charts.

Adele's record-breaking "25" is still seeing strong sales three months after its release with 116,000 total units sold in the past week, comprising album and song sales and streaming activity, according to figures from Nielsen SoundScan.

Rihanna's eighth album "Anti" was released on Jan. 27 exclusively on online music platform Tidal, which charges users upwards of $10 a month. It was released on all other digital platforms, including iTunes and Amazon, two days after the Tidal exclusive.

"Anti" sold under 500 albums but through a deal with Samsung, a million copies were offered free to fans who signed up for Tidal membership, making them ineligible for Billboard charts rankings, which does not count sales of albums priced under $3.49.

It is likely to climb the chart next week after a full week of sales and release of the physical album in stores on Friday.

Through sales of lead single "Work," which clocked 126,000 digital downloads and took the top spot on the Digital Songs chart, and more than 4 million streams, "Anti" came in at No. 27 on the Billboard 200 chart.

Only two new entries debuted in the top 10 of the Billboard 200 chart this week: Heavy metal group Megadeth's latest album "Dystopia" opened at No. 3 and the 2016 Grammy nominees album, featuring hits by Kendrick Lamar, Taylor Swift and The Weeknd.

(Reporting by Piya Sinha-Roy, editing by Jill Serjeant and Grant McCool)