How do I escape ampersands in batch files?

How do I escape ampersands in a batch file (or from the Windows command line) in order to use the start command to open web pages with ampersands in the URL?

Double quotes will not work with start; this starts a new command-line window instead.

Update 1: Wael Dalloul's solution works. In addition, if there are URL encoded characters (e.g. space is encoded as %20) in the URL and it is in a batch file then '%' must be encoded as '%%'. This is not the case in the example.

Example, from the command line (CMD.EXE):

start http://www.google.com/search?client=opera&rls=en&q=escape+ampersand&sourceid=opera&ie=utf-8&oe=utf-8

will result in

http://www.google.com/search?client=opera 

being opened in the default browser and these errors in the command line window:

'rls' is not recognized as an internal or external command,
operable program or batch file.
'q' is not recognized as an internal or external command,
operable program or batch file.
'sourceid' is not recognized as an internal or external command,
operable program or batch file.
'ie' is not recognized as an internal or external command,
operable program or batch file.
'oe' is not recognized as an internal or external command,
operable program or batch file.

Platform: Windows XP 64 bit SP2.

From a cmd:

• & is escaped like this: ^& (based on @Wael Dalloul's answer)
• % does not need to be escaped

An example:

start http://www.google.com/search?client=opera^&rls=en^&q=escape+ampersand%20and%20percentage+in+cmd^&sourceid=opera^&ie=utf-8^&oe=utf-8

From a batch file

• & is escaped like this: ^& (based on @Wael Dalloul's answer)
• % is escaped like this: %% (based on the OPs update)

An example:

start http://www.google.com/search?client=opera^&rls=en^&q=escape+ampersand%%20and%%20percentage+in+batch+file^&sourceid=opera^&ie=utf-8^&oe=utf-8