Pecker is a key witness in the case against the former US president, who is accused of falsifying business records to cover up hush-money payment
It is the first time that the Arab world’s poorest country has staged the annual tournament since its launch in 1970.
Iraq and the six oil-rich Gulf states will be competing with Yemen in the tournament which continues until December 5.
Matches will be played in the main southern city of Aden and in nearby Zinjibar, capital of Abyan province.
The authorities have mobilised some 30,000 police to provide security at the stadiums and around the visiting teams’ hotels, the tournament’s security chief General Saleh Zawara said.
He said there would be six security cordons around each of the venues.
On Tuesday, activists of the Southern Movement, a coalition of autonomist and pro-independence groups, vowed in a statement to try to disrupt the tournament.
Yemeni prosecutors implicated one of the movement’s leaders, Shalal Ali al-Shaea, in twin bomb blasts in Aden in October.
The south was independent from 1967 when the British withdrew until it united with the north in 1990.
It seceded in 1994, sparking a brief civil war that ended with it overrun by northern troops.
Many residents complain of discrimination by the Sanaa government in the distribution of resources and the region has seen a spate of violent protests in recent months.
It has also witnessed growing violence by Al Qaeda, which has found safe haven in the south and east of Yemen, Osama bin Laden’s ancestral homeland.
Yemeni officials have been at pains to reassure the countries taking part in the Gulf Cup that the tournament can go ahead safely.
President Ali Abdullah Saleh visited Aden on Friday, where he inspected the facilities for the tournament and held meetings with organisers and security officials.
Saleh paid tribute to”the efforts of the security services and military to ensure that the tournament takes place peacefully and securely”.
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