LONDON (REUTERS) - Britain's interior minister said a claim by United States President Donald Trump that the culprits behind a bombing on a London train were in the sights of the police, made on Twitter shortly after the attack, had been nothing more than speculation.

"It's never helpful to have speculation about an ongoing operation and I would include the president of the United States in that comment," Amber Rudd told BBC television on Sunday (Sept 17).

"It is pure speculation, absolutely."

Rudd's comments echoed those of British Prime Minister Theresa May who said on Friday it was not helpful for anyone to speculate on investigations.