Katy Perry and Orlando Bloom have sparked romance reunion rumours after being spotted together at an Ed Sheeran concert in Los Angeles.

Bloom, who dated Perry for almost a year before they announced their split in February, was seen with his arms around the singer at the show in the Staples Centre on Saturday night.

"They definitely seemed like they're back together," an eyewitness told E! News.

"They cuddled most of the night. She sat on his lap most of the night and shared kisses."

Both stars were dressed casually with black baseball hats; with the witness saying, "People didn't really bug her. I don't really think people knew it was them because they had hats on and stuff."

The pair began their relationship after last year's Golden Globe awards, with a statement released in February saying they were to take some time apart.

"Before rumours or falsifications get out of hand, we can confirm that Orlando and Katy are taking respectful, loving space at this time," a statement from their representatives read.