"Harry Potter" star Daniel Radcliffe may have cast a spell on co-star Emma Watson, U.K.'s The Mirror reports.

Radcliffe, 18, and Watson, 17, who plays Hermione Granger in the blockbuster productions based on J.K. Rowling's books, were spotted on Valentine's Day huddled together in the garden of a London bar. The pair were apparently taking measures not to be seen, the Mirror reports.

"They arrived quite late at the pub — about 10 p.m. — and sat outside, using each other's bodies for warmth," an onlooker told the Mirror. "Emma kept looking over her shoulder nervously as if she didn't wanted to be recognized."

The teen actors have known each other since filming the first "Harry Potter" installment seven years ago, but have never before been romantically linked.

Filming started recently for "Harry Potter and the Half-Blood Prince," the sixth movie in the hit series. Radcliffe, who turned 18 over the summer, was 11 when he was first cast as the schoolboy wizard. British newspapers have estimated that he has a total net worth of $35 million.

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