Security at the Australian Open will be tightened after pro-Russian displays among Djokovic's fans

Security is expected to be further tightened at the Australian Open over finals weekend after Novak Djokovics presence sparked another heckler incident, plus displays of pro-Russia sentiment among his fans.

Despite clear restrictions and searches at entry points, a Russian flag with Vladimir Putins face on it was unfurled on the steps of Rod Laver Arena after Djokovic made it through to the semi-finals.

Another of his supporters sat in the front row and unveiled a T-shirt with a large Z on it, the emblem of the Russian army.

This was despite the nine-times champion playing a Russian, Andrey Rublev, who he crushed 6-1 6-2 6-4 as he went marching on towards another title.

Later a picture emerged of Djokovic signing something for the man in the Z shirt, although by then it appeared he had covered it up.

Afterwards a group of fans chanted Russia, Serbia in a reminder of the two countries close cultural ties, and the sympathy that some from the latter have towards Putins war in Ukraine.

Four people in the crowd leaving the stadium revealed inappropriate flags and symbols and threatened security guards, said Tennis Australia in a statement.