Lily Allen has denied mocking pop rival Amy Winehouse during a recent festival performance.The 'Smile' singer insists her toast to the 'Rehab' star who recently collapsed after an alleged alcohol and drugs overdose - during her V-Festival set in Chelmsford on Sunday, wasn't meant to cause offence.Writing on her blog, Lily said: "Me raising a drink to Amy was just that, showing my support for her. I've been around enough alcoholism to know that it is a serious matter."Lily was accused of mocking Amy when she poured herself a shot of Jagermeister, a 70 per cent proof liqueur, and said: "It's the end of the weekend, you have got to have a drink. Here's to Amy Winehouse... ha!"Meanwhile, Amy - who quit rehab for the second time on Sunday - has pulled out of a series of concerts in the US and Canada in order to "address her health". Amy's spokeswoman Tracy Miller said: "She has been advised to postpone her North American shows until next year."Until then, Amy has been ordered to rest and is working with medical professionals to address her health."Amy's UK concert dates in October and November are still set to go ahead.