abline in log-log power law plot

I have a power law plot in log-log scale using plot(x,y,log="xy") but I
can't get the regression line to plot correctly.
abline(lm(log(y)~log(x))) plots a straight line that looks promising but
the intercept with the y-axis seems to be way off.
summary(lm(log(y)~log(x))) gives the values but i cant really make any
sense out of it.
fitted(..) just confirms the values that seem to be incorrect.
any help is appreciated.
thanks!

martin