The victims, all of whom survived, were said to have sustained injuries similar to those inflicted by Sutcliffe.
The Bradford lorry driver was jailed in 1981 for 13 murders and seven attacks during a six-year period in which the county was convulsed with fear.
West Yorkshire Police yesterday declined to comment on a report in a national newspaper, which said some of the unsolved cases involved the same kind of hammer used by Sutcliffe.
But the force has acknowledged previously that it is conducting an “ongoing investigation” into historical cases connected to the Ripper in a 1982 report by a former inspector of constabulary, Sir Lawrence Byford.
The new round of questioning was said to have been conducted at Frankland Prison in Durham, to which Sutcliffe, 70, was moved last summer after a ruling that he no longer needed to be housed in a secure hospital.
Among the cases linked to him is that of 20 year-old Mo Lea, who was attacked in October 1980, near Leeds University.
Other unsolved cases include a 1979 attack on student Ann Rooney, 22, in Horsforth, Leeds, and an assault on Tracy Browne who, at 14, was hit with a hammer in Silsden, near Keighley, in August 1975, two months before Sutcliffe claimed his first murder victim.
Police are also said to be investigating the case of Yvonne Mysliwiec, who was a local newspaper reporter in Ilkley.
The Byford Report, which was only made public in 2006, concluded that Sutcliffe could have been responsible for 13 more offences. It said there was an “unexplained lull” in his activities between 1969, when he first came to the police’s attention, and the date of his first conviction in 1975, and that it was “highly improbable” that his known crimes were the only ones attributable to him.