KAZAN, Russia (AFP) - The United States are having a disappointing world swimming championships by their own high standards and Olympic backstroke champion Tyler Clary slammed the American media on Thursday for some negative coverage.

The team are currently third in the medal table, having finished top at all of the last six world aquatics championships, dating back to Fukuoka, Japan, in 2001 when Australia claimed first place.

Teenager Katie Ledecky has been America's outstanding performer in Kazan after twice breaking the women's 1,500m freestyle world record and winning three freestyle golds with the 800m still to come.

But with US star Michael Phelps missing in Russia after his drink-driving conviction last year, some of the Stars and Stripes' top names have failed to dominate the racing here as they usually do.

It has led to some criticism from back home and Clary was not happy about some of the things he has read online.

The US failed to win a single heat on Thursday morning as Clary went on the attack.

"To be honest, I am tired about hearing how the Americans are doing here," said Clary, who took bronze in the 200m backstroke in Barcelona two years ago and gold at the London 2012 Olympics.

"One year from now (at the Rio de Janeiro Olympics), no one will be talking about what happened here. I am tired of some of the negative comments.

"We're all sticking together as a team."

Clary was sixth in the men's 200m backstroke heats as Australia's Mitchell Larkin, who won the 100m title on Tuesday, posted the fastest time of 1min 55.88sec n the evening's semi-finals.

Missy Franklin of the US left the Barcelona championships two years ago with six golds.

The 20-year-old has only two bronzes so far in Kazan and was 10th fastest in the morning's 100m freestyle heats to reach the semi-finals.

"We all know our priority is to get to the Olympics next year," said Franklin.

"Sometimes we get disappointed and so do our fans, but we're doing the best we can."