South Africa have cancelled their tour of Pakistan because of security concerns, the United Cricket Board said on Saturday.

The tour had been given the go-ahead on Thursday, but the UCB decided to call it off after a bomb blast in Karachi on Friday.

South Africa were due to leave on Sunday.

"The UCB regrets that South Africa is unable to tour Pakistan at this time due to yesterday's bomb blast in Karachi and the deteriorating security situation in Pakistan," UCB media officer Gerald de Kock said by telephone from Johannesburg.

De Kock said there is still hope the two teams could meet at an alternative venue. "The UCB has offered the Pakistan Cricket Board the option of playing the series in South Africa or at a neutral venue," he said.

EARLIER: SA to decide on tour tonight