Singer Nicole Scherzinger has reportedly rejected Formula 1 driver Lewis Hamilton's marriage proposal thrice in a month.

Hamilton and Scherzinger rekindled their romance over Christmas 2013 after parting ways in July last year.

The 35-year-old has even moved her stuff into Hamilton's Monaco pad.

Hamilton, 29, is desperate to seal their relationship with a big summer wedding, however sources said that Scherzinger keeps saying no, reports dailystar.co.uk.

"Lewis is so desperate to hold on to Nicole this time around that he keeps asking her to marry him. But she's playing very hard to get. She thinks if she holds out Lewis will respect her more and not take her for granted like he has in the past," said a source.

"Lewis really wants to get engaged properly and then start planning a wedding for early August when he has a three-week break in the Formula One schedule. Nicole keeps rejecting him and is saying 'I need time to think about what I want.'," the source added.

Despite his girlfriend's stubbornness, Hamilton is convinced that she will say yes within a month.

"He's going to keep asking until he gets his way. Nicole is building a proper life with him again and spends every free second with him. So, as far as he is concerned, it's a matter of when rather than if."

"He has told his closest friends to keep the first two weeks of August free for a 'mind-blowing wedding'. Now all he needs is for her to agree to it," said a source.