Morgan, who edited Britain's Daily Mirror newspaper between 1995 and 2004, said he attended a voluntary interview with detectives.
"As this is an ongoing investigation, I am unable to comment further until its conclusion," he said in a statement. London's Metropolitan Police said "a 50-year-old man was interviewed under caution ... In connection with suspected conspiracy to intercept telephone voicemails." "Under caution" means Morgan was not arrested, but the interview was recorded and could be used in future prosecutions
Morgan, 50, was previously questioned by police investigating hacking in December 2013.
Since then, police investigations, criminal trials and a public inquiry have revealed that phone hacking was widespread at Britain's tabloids more than a decade ago.