This is the young growth of the dreaded Japanese Knotweed and getting rid if it is very difficult. The best method is said to be by breaking the stems and dribbling roundup down them. This will still take many years. If you try to dig them up they may be burned on site but it is illegal to put them in the waste bin. Any dug up material has to be sent to a specielly licenced waste site. The local authority and SEPA will know details of this.

oh yes it looks like Japanese knotweed. destroy and do not compost it as BA says.

ouch i dug mine up and after a couple of years of pulling every shoot up with roots i sore it has at last gone.