[R] xts array in minutes ?

ce
2014-10-11T16:03:07Z

Dear all,

I want to convert to character arrays  "2014-10:10 00:00:00" and
"2014-10-10:23:59:00" to an array of minutes :

2014-10:10 00:00:00
2014-10:10 00:01:00
2014-10:10 00:02:00

What is the best way to do it ?
thanks