CAPE TOWN - Desmond Tutu's daughter says it's not clear how long her father will be hospitalised.

Mpho Tutu says the Arch is on a course of antibiotics that could take three to five days or longer.

The 83-year-old was admitted to a Cape Town facility after failing to respond to oral treatment earlier this week.

She says doctors are satisfied his cancer has remained dormant.

Tutu adds the Arch is being treated by a team of world class doctors, in a first class facility.

He's reportedly in good spirits.

Addressing the media at the Desmond and Leah Tutu Foundation today, Tutu said the course could be up to five days or more.

MESSAGES OF SUPPORT

Earlier today, President Jacob Zuma joined other South Africans in wishing the Arch a speedy recovery.

Zuma asked South Africans to keep Tutu in their thoughts and prayers.

The Anglican Archbishop Thabo Makgoba also offered words of support.

In a statement, Makgoba joined many well-wishers, saying he hopes Tutu will be able to go home to his family soon.

On Wednesday, Rivonia trialist Ahmed Kathrada said he was optimistic that Tutu would make a speedy recovery.

Kathrada also sent his well wishes to the 83-year-old.

"We wish and pray that he will recover as soon as possible."

Tutu previously underwent treatment for a persistent infection two years ago.

He has been living with prostate cancer for the past 15 years.

The Arch Desmond Tutu kept in hospital for treatment. We wishe the Archbishop and all our elders who are not well a speedy recovery

• Tim Modise (@TimModise) July 16, 2015

@Radio702 A speedy recovery indeed, he (Archbishop Desmond Tutu) is our voice of reason in trying times and a sage and a source morality.

• SAMKELO18 (@SAMKELO18) July 15, 2015

Archbishop Desmond #Tutu was hospitalised yesterday for a "persistent infection." We wish him a speedy recovery. pic.twitter.com/XXZZG1rv7Q

• Yusuf Abramjee (@Abramjee) July 15, 2015

I met Desmond Tutu once, it was one of the highlights of my life. Plenty of joyous laughing and high-fiving. He's a total legend.

• Kerron Cross (@KerronCross) July 16, 2015

[Listen] President Jacob Zuma wishes Archbishop Emeritus Desmond Tutu a speedy recovery. https://t.co/9iuxmGiptk

• South African Gov (@GovernmentZA) July 16, 2015

ANC wishes Archbishop Desmond Tutu a speedy recovery: http://t.co/cAZwCAUrwJ pic.twitter.com/QH98KYiYL6

• ANC Info Feed (@MyANC_) July 15, 2015

Wishing The Arch a speedy recovery. Arch Tutu is not only a spiritual and moral voice, but a hero and inspiration. Our prayers are with u.

• Mmusi Maimane (@MmusiMaimane) July 16, 2015

Wishing our outspoken and fearless Arch Tutu a speedy recovery. You are the conscience of our nation.

• Vusi Pikoli (@VusiPikoli) July 16, 2015

We send our love and support to Bishop Tutu and wish him a speedy recovery @TheDesmondTutu @PublicProtector

• Adv Thuli Madonsela (@ThuliMadonsela3) July 15, 2015