Hillsong Senior Pastor Brian Houston has issued a letter of apology for failings at the Church's East Coast campus in the US.

The apology was contained in an email to Hillsong members on Thursday, Religion News Service reports, and comes four months after the departure of its scandal-hit former pastor, Carl Lentz.

Lentz was sacked over "moral failures" and the once celebrity pastor later admitted to adultery. But his departure sparked a wave of accusations against the NYC church leadership, particularly around expenses and the treatment of celebrities. 

"We know that Hillsong East Coast has failed to be the kind of church it should be. On behalf of the Global Board and as Global Senior Pastor, I accept responsibility for these failings and apologize unreservedly," Houston wrote this week. 

An internal investigation into Hillsong East Coast concluded last month without the findings being made public.  Houston said the investigation confirmed that the campus had failed to reflect the global Hillsong culture in "significant ways".

Attached to Houston's email this week was a letter from Zukerman Gore Brandeis & Crossman, the New York City lawfirm behind the investigation, which said that the detailed report would "not be released to the public to protect the privacy and confidentiality of those involved", RNS reports.

The email promised a number of changes "to address the lapses that have affected the culture of our East Coast campuses" and prevent policies "from being ignored."

Changes include the introduction of financial safeguards, a "stringent" sexual misconduct and harassment policy, and "a clear and consistent system for reporting grievances and issues related to inappropriate behaviour." 

Other training will seek to raise awareness among staff "of the specific types of power dynamics that often arise in a church setting."

"Policies will be added to ensure that all positions are compensated fairly and equitably," it added.

Chrishan and Danielle Jeyaratnam, leaders of Hillsong Perth, in Australia, were recently confirmed as the new leaders of Hillsong East Coast. 

Houston also announced last month that he and wife Bobbie would be stepping back from global leadership. The next two years will see UK pastors Gary and Cathy Clarke assume greater responsibility at the international level.