Optimal lags extraction

Hello,
I am using `urca::ur.df` and in subsequent analysis I would like to use the optimal number of lag that this function finds according to BIC. Unfortunately, the object produced by

`obj<-ur.df(data, 'none', 'BIC')`

does not present what inside the function is found with `which.min(critRes)`. It could be useful to add this as a hidden but accessible information. 