* Rich nations take first step toward ending rescue steps

* IMF to help plot withdrawal of stimulus policies

* Countries say signs of economic recovery still shaky * Differences persist on bank stress tests

* Ministers bemoan return of excessive market speculation

(Adds analyst comment, ministers' criticism of speculators)

By Anna Willard and David Lawder

LECCE, Italy, June 13 (Reuters) - The world's rich nations, heartened by signs the credit crisis is easing, have started to consider how to unwind rescue steps for their economies once recovery is certain, their finance ministers said on Saturday.

Meeting in southern Italy, the ministers described their economies in the most positive terms since the collapse of Lehman Brothers nine months ago ushered in the world's worst financial crisis since the Great Depression of the 1930s.