shares of petra diamonds ltd fell 91 on thursday after the company said that it expects production from the williamson mine in tanzania to be suspended for up to three months following flooding in the area shares at 1431 gmt were down 100 pence at 1000 pence the londonlisted mining company said on monday that there had been a wall beach at the tailings storage facility at the williamson mine resulting in flooding which had extended into areas outside of the mine lease area production was suspended at the time detailed planning is underway to bring a new tsf into operation which was already under construction at the time of the incident and which requires construction of a new wall on the boundary of the failed tsf the company said thursday it added that until production can be started the planned maintenance will be brought forward along with accelerated waste stripping petra has a 75 shareholding in williamson diamonds ltd with the government of tanzania owning the rest