Under-fire megachurch pastor Joel Osteen has hit back at critics who claim he initially refused to open his 16,000 capacity building to flood victims after Hurricane Harvey in Texas.

In an unusually short address to a congregation on Sunday morning he said: 'There's been so much misinformation about the church this week, I wanted to clarify some things.'

It comes after several days of controversy where Osteen's Lakewood Church in Houston was criticised after widely circulated images online showed the building, formerly a basketball stadium for the Houston Rockets, locked and barred immediately after the flooding.

After receiving nationwide coverage and coming under intense pressure, Lakewood Church opened its doors to those who had lost their homes in the flooding.

'Houstonians, Texans, are generous people, gracious people. We like to help others in need. That's what you're seeing here today people stepping up and you know and helping these people that have been displaced,' Osteen said on Tuesday, announcing the opening of the 16,000-seat arena belonging to his congregation, Lakewood Church.

Justifying the delay, Osteen backed comments made by Lakewood Church spokesman Don Iloff saying the building had initially been flooded, making it unsafe as a shelter.

'This building flooded in 2001, when the Rockets were still playing basketball here,' Osteen said on Sunday. 'It was over five feet of water in this lower bowl. Knowing that, when we took possession, we installed large flood gates around the building.'

The hurricane floodwater came within a foot or two of reaching the new gates and flooding the building again, he said.

'So [it] receded late Sunday, maybe early Monday; we felt it was safe to start taking people in on Tuesday. I don't mind taking the heat for being precautious [sic], but I don't want to take the heat for being foolish.'

He later told Fox News: 'There was safety issues that people didn't see. They see this building sitting up on a high hill, looks like a high hill, but behind the building is where the water comes in. And so our flood gates were keeping the water out until, I'm told, Sunday night or maybe even early Monday.'

He went on to say no one had been turned away. Even when the building was closed, three people came and asked for shelter and they were welcomed in by security, he said.