The Chair of the National Assembly's Finance Committee, Simon Thomas AM, has issued the following statement:
Mr Thomas said:
"This Committee is frustrated and disappointed at the continuing reticence of the Secretary of State for Wales, the Right Honourable Alun Cairns MP, to appear before us on matters essential to the governance and performance of Wales.
"Thorough scrutiny and accountability are critical parts of any minister's portfolio, regardless of the institution in which they sit.
"This Committee's work is considering matters which will affect every person in Wales, including the devolvement of tax-raising powers later this year. The Secretary of State is statutorily obliged to report on the implementation of the Wales Act 2014, but will not attend Committee to discuss these annual reports.
"It is critical such processes are rigorously examined and that all parties involved subject themselves to such scrutiny."
The Finance Committee has offered a number of dates to the Secretary of State for Wales to appear before the Committee since May 2016, including the option of appearing via video conference or Skype for convenience.