A dropped baton cost the United States a clean sweep of the world relay titles.

The women's 4x400m team were leading Jamaica going into the final changeover, but when Michelle Collins handed the baton to Suziann Reid, the final-leg runner tried to transfer it from her left hand to her right and only succeeded in dropping it to the floor.

Reid picked it up and continued but by that time she was fifth and only improved to fourth in the final few strides, overtaking Great Britain's Catherine Murphy.

Jamaica's team of Sandie Richards, Catherine Scott, Debbie-Ann Parris and Lorraine Fenton were left to take gold in 3.20.65, followed by Germany and Russia.

Britain did well to finish fifth in 3.26.94. Their team of Lee McConnell, Helen Frost, Natasha Danvers and Murphy was missing arguably its four strongest runners.

Katharine Merry, Donna Fraser and Allison Curbishley were injured, while Lesley Owusu was still recovering from dehydration which had seen her leave the track in a wheelchair on Saturday.

Gold medallist Fenton said: "I feel sorry for the Americans, but it gave us the boost we needed. We all put in a team effort.

"In the relay we all have to come together and we did."