WASHINGTON — Veterans Affairs Secretary Eric Shinseki said he is angry and saddened by allegations of treatment delays and preventable deaths at a Phoenix veterans hospital.

“Any adverse event for a veteran within our care is one too many,” Shinseki said in prepared testimony for a Senate hearing today on the Phoenix allegations and other problems at the VA. “We can, and we must do better.”

Appearing before the panel amid calls from some Republicans and veterans groups to resign, Shinseki vowed to hold employees accountable for any misconduct.

Shinseki has said he welcomes a White House review of his beleaguered department after allegations the Phoenix hospital maintained a secret waiting list to hide lengthy delays for sick veterans. A former clinic director says up to 40 veterans may have died while awaiting treatment at the Phoenix facility.

“If allegations about manipulation of appointment scheduling are true, they are completely unacceptable — to veterans, to me and to our dedicated VA employees,” Shinseki said.

The hearing before the Senate Veterans Affairs Committee comes as President Barack Obama has assigned White House deputy chief of staff Rob Nabors to work on a review focused on policies for patient safety rules and the scheduling of patient appointments. The move, announced late Wednesday, signals Obama’s growing concern over problems at the VA.

Problems similar to those that surfaced in Phoenix have since been reported in other states.

The American Legion and some congressional Republicans have called for Shinseki to resign, a move he and the White House have resisted. The VA’s inspector general is investigating the Phoenix claims, and Shinseki has ordered an audit of VA facilities nationwide to see how they provide access to care.