Residents of Mariupol dig trenches as they assist Ukrainian troops in organising their defence on the outskirts of the southern Ukrainian city of Mariupol on August 29, 2014
Mariupol (Ukraine) (AFP) - Residents in east Ukraine's strategic port Mariupol dug trenches Friday as others packed up and fled over fears the city could be the next target for advancing pro-Russian rebels.
AFP journalists saw dozens of people building hasty defences in a field on the eastern outskirts of the government-held city, after pro-Moscow forces that Kiev claims are actually Russian troops, captured a town some 30 kilometres (20 miles) away.
Others brought food and supplies to the makeshift barricades where Ukraine's National Guard and volunteer fighters were trying to prepare for an attack from the direction of the Russian border.
The pro-Kiev regional governor -- based in Mariupol since being kicked out of the city of Donetsk by rebels -- issued an appeal to residents to rally together into an "effective self-defense force for the city".
"We have a chance today to create Ukraine's history," Donetsk region governor Sergiy Taruta said. "Each of us has to decide what he can do for his country."
Indeed several thousand residents in Mariupol - the heart of east Ukraine's metals industry - had gathered Thursday evening to show their support for Kiev by waving Ukrainian flags and holding up posters reading "Putin go away".
But by Friday many others clearly thought it was time to leave the threatened city.
Local inhabitants could be seen driving north from the city with buses crammed full of people displaying signs with "children" written on them, in the hope they would not be fired on.
Some may have been fleeing for a second time, having come to the city as refugees from fighting around Donetsk.
Mariupol, a major hub of about 500,000 people on the Azov Sea, is the next city along the coast after the town of Novoazovsk, which was seized from pro-Kiev fighters Wednesday after days of brutal fighting.
- Sweeping counter-offensive -
Kiev has admitted its forces no longer control Novoazovsk, and rebels have said in no uncertain terms that their plan is to "liberate" Mariupol next as part of a sweeping counter-offensive to win back territory captured by Kiev.
The rebel leadership of the self-proclaimed "Donetsk People's Republic" has also said that the rebels now control the border with Russia, across which Kiev and the West say Moscow has sent a flood of weapons and fighters.
To the north of the city an AFP correspondent said that the towns of Telmanove and Komsomolske, lying between Mariupol and Donetsk, were still controlled by the Ukrainian army Friday.
While fears are now mounting of a looming battle for the city, it would not be the first time that Mariupol has been fought over during the more than four months of brutal conflict between government forces and rebels in east Ukraine.
Pitched battles in the city killed over a dozen people in May and a police station was torched, but the army ousted separatists soon after.