A review of the impact of PD rights on housing quality was announced by former housing secretary James Brokenshire in last year's Spring Statement.
At the time, Brokenshire said: "I intend to review permitted development rights for conversion of buildings to residential use in respect of the quality standard of homes delivered."
The Coalition government introduced PD rights for office-to-residential conversions and larger single-storey home extensions in 2013, both of which are considered by councils under a light-touch prior approval process.
Since then, a number of other PD rights for residential conversions have been introduced, including for agricultural and light industrial buildings.
But the policy has prompted growing concerns about its impact on housing quality, with the Town and Country Planning Association (TCPA) launching a campaign against residential PD rights and criticism by the Local Government Association.
Last week, a report by former Labour housing minister Nick Raynsford, commissioned by the TCPA, renewed his call for ministers to immediately revoke "damaging permitted development rights" and said "government policy has led directly to the creation of slum housing".
It claimed that evidence of PD rights producing poor quality housing "is now overwhelming", while the policy was "corrosive" to the morale of local authority planners.
In response to the concerns raised in Raynsford's report, an MHCLG spokesman said: "Permitted development rights have delivered over 60,000 homes and will continue to play an important role in making our commitment of one million new homes built by the end of this parliament a reality.
"But we’ve also got to get the quality of these new homes right - our review will be completed shortly and an announcement on its findings will be made in due course."
According to the MHCLG, between April 2015 and March 2019 a total of 60,399 new homes were delivered through PD rights, with 54,162 of them through the office-to-residential PD right.
Speaking at the Conservative Party conference last October, housing secretary Robert Jenrick said the government had "learned from some of the concerns" of the introduction of office-to-residential PD rights and admitted that the controversial relaxation of planning rules has produced some "very bad examples".
He added that the review was examining the "first wave" of PD rights, particularly office-to-residential, and assessing "whether there is evidence on a material level of poor-quality properties" such as those not built to last and those that "will cause problems for future generations".
Also at the Tory conference in October, housing minister Esther McVey said where PD rights were "not working", the government would be "changing the rules" around to improve housing standards.
Raynsford's report was an update to the November 2018 Raynsford Review of Planning, which called for urgent action to improve the planning system.
Earlier this month, a report by the LGA claimed that more than 13,500 affordable homes have been lost over the past four years as a result of developers using PD rights, which do not require applicants to contribute to affordable housing.