In a negligence action to recover damages for personal injuries, etc., defendant appeals from an order of the Supreme Court, Richmond County, dated December 20, 1977, which granted plaintiffs' motion to strike his answer and directed an assessment of damages. Order reversed, without costs or disbursements, and motion denied, without prejudice to the commencement of proceedings pursuant to CPLR 3106 (subd [c]). In view of the fact that defendant-appellant was incarcerated at the time that his examination before trial was scheduled pursuant to notice by plaintiffs-respondents, he did not willfully fail to appear for the examination within the meaning of CPLR 3126 and its related sections (see Goldner v Lendor Structures, 29 A.D.2d 978). Further, the striking of an answer is an extreme penalty and, in the interests of justice, should not be invoked absent a conclusive showing that the default in disclosure was clearly deliberate and contumacious (see Shaw v Stewart Franklin Apts., 49 A.D.2d 892; Matter of Colon v Department of Personnel, 56 A.D.2d 538). Latham, J.P., Damiani, Shapiro and Margett, JJ., concur.