Hillsong has apologised after senior pastor Brian Houston was investigated over allegations of "inappropriate" texts and entering a woman's hotel room. 

In a statement on Friday, the Church's Global Board said that there had been "a significant breach of trust" and that in one of the two incidents, Houston "had breached the Hillsong Pastor's Code of Conduct".

The first complaint goes back a decade and is said by the board to have involved "inappropriate" text messages from Houston to a Hillsong staff member who subsequently resigned. The staff member's identity has not been disclosed. 

The board said this incident occurred while Houston was dependent on sleeping tablets and that he had apologised and received treatment.

"At the time, Pastor Brian was under the influence of sleeping tablets, upon which he had developed a dependence. He immediately apologised to the person," the statement said.

"We also worked closely with Pastor Brian to ensure he received professional help to eliminate his dependency on this medication, and this was achieved successfully.

"To this former staff member, we again apologise and would welcome the opportunity to provide further assistance if this is needed." 

The second complaint was received in 2019 from an unnamed woman who said Houston had entered her hotel room. The woman subsequently asked for the refund of a donation she had made to the Church, which Hillsong agreed to.

The board said Houston "was extremely remorseful" and "insisted on repaying the Church" for the money it lost from the refund. 

"Following an in-depth investigation, it was found that Pastor Brian became disoriented after a session at the Hillsong Conference, following the consumption of anti-anxiety medication beyond the prescribed dose, mixed with alcohol," the board said.

"This resulted in him knocking on the door of a hotel room that was not his, entering this room and spending time with the female occupant.

"The investigation by the integrity unit appointed by the global board found that although all parts of the complaint were unable to be sustained, important elements of the complaint were sustained and the conduct was of serious concern.

"Ultimately, the board found that Brian had breached the Hillsong Pastor's Code of Conduct.

"We also acknowledge that whatever the circumstances at this time, this person did not deserve to be placed in the situation she found herself in by Pastor Brian." 

The board said the investigations had been conducted either by board members or a body appointed by the global board to hear and resolve complaints against credentialled pastors. 

They were also "assisted by highly respected external pastors and advisors".

Following the investigation into the 2019 complaint, the board said Houston agreed to take "specific action including stepping down from leadership for a period".

It added that Houston had "failed to take all of the agreed steps which resulted in further action being taken by the board in late 2021". The board did not divulge what that action was. 

"We apologise unreservedly to the people affected by Pastor Brian's actions and commit to being available for any further assistance we can provide," the board said.

Houston has been on leave since stepping down as senior pastor earlier this year ahead of an upcoming trial over allegations that he concealed knowledge of his father's abuse.

In the statement, the board said it was seeking external counsel in a review of its governance model which has "historically placed significant control in the hands of the senior pastor". 

"We know there are areas on which we can improve, and we will work honestly and transparently to that end," it said.