STUTTGART, GERMANY (AFP) - US gymnastics star Simone Biles clinched a record-extending 15th world championship gold medal on Tuesday (Oct 8) as the Americans won the women's team title in Stuttgart.

Biles, 22, collected her 21st medal at the championships to become the most decorated women's gymnast, taking her one clear of Russia's Svetlana Khorkina.

She also moved to within two medals of the all-time record held by Vitaly Scherbo of Belarus, a men's gymnastics star in the 1990s.

It was a fourth team title for Biles in an event the Americans have dominated for the last eight years.

They claimed gold with a tally of 172.330, well ahead of the Russians who took silver with 166.529, while bronze went to Italy on 164.796.

Biles played a key role in a commanding performance by the USA, earning the most points in three of the four disciplines - the vault, balance beam and floor.

She earned a loud cheer for landing the "Biles II" skill - a triple-twisting double back on the floor - keeping her pre-championship promise to perform it in "every competition" in Stuttgart.

Her huge tally of 15.333 led a US clean sweep in the floor exercises alongside team-mates Jade Carey and Sunisa Lee, to hand the Americans gold.

Biles is expected to add more medals to her dazzling tally as the favourite in the women's all-around final on Thursday and this weekend's apparatus finals.