The source said the troops arrived in Yemen's second city yesterday with tanks and armoured vehicles. He gave no further details.
The Saudi-owned Al-Hayat newspaper reported today that a total of 1,500 troops, most of them from the United Arab Emirates, had reached Aden.
The UAE is a member of the coalition which has carried out more than four months of air strikes against the rebels who overran much of Yemen in March, forcing President Abderabbo Mansour Hadi into Saudi exile.