The thrust towards the southern city, headquarters of Yemen's Vice- President Ali Salem al-Baidh, was the north's ninth attempt to cross the old border between former North and South Yemen, Aden radio said.
'It looks like we are moving towards stalemate,' one Western analyst said of rival victory claims that have marked seven days of fighting.
The northern military, loyal to President Ali Abdullah Saleh, said yesterday its forces downed two southern Sukhoi fighter-bombers in Monday's battles for control of the approaches to Aden.
It repeated claims that northern forces were only 5km (3 miles) from the port city, saying one brigade was in Dar Saad on the outskirts while other forces were advancing from other fronts.
Aden says northern troops have been cleared from the approaches to the city and fighting now centred on the three border districts, in the mountainous regions about 100km north of Aden.
The southerners denied that northern forces were anywhere near Dar Saad suburb.
The military hospital in Sanaa counted a total of 119 dead and 507 wounded in the fighting. It did not say how many were northerners and southerners.
The statement appeared to support Western reports that the north had run into stiff resistance in its bid to advance on the city.
In London yesterday the human rights group Amnesty International said it had received reports of widespread arrests of civilians in Yemen. Scores of people were being held incommunicado by northern police and military, it said.