I think he can. In general he has no control and ends up spraying
the ball. Would be very useful if he learnt that. People are making too
much about ability to produce reverse swing. That said, I don't
think I will question the fact that he can produce reverse swing.

Quick search on Google gave these links.

First  one is an Danny Morrison's interview
http://us.rediff.com/cricket/2003/oct/15inter.htm

http://www.rediff.com/cricket/2000/dec/11india.htm

http://www.rediff.com/cricket/2000/dec/14india.htm

http://www.hindustantimes.com/news/specials/natwest/profile/agarkarprofile.shtml

http://www.sportstaronnet.com/tss2426/24260220.htm

http://www.cricket.org/link_to_database/ARCHIVE/CRICKET_NEWS/2000/NOV/063401_IND
_27NOV2000.html

N[Hope this settles the issue]