Macedonia has begun building a new razor-wire fence parallel to an existing one on its border with Greece to make it harder for migrants to enter the Balkan country, an army official said Monday.

Since November only refugees from Syria, Afghanistan and Iraq have been allowed to cross the border on their journey to western Europe, but migrants from other countries have still tried to get across.

‘The idea is to send a message to migrants that there is a double fence so give up crossing illegally,’ a senior army official who requested anonymity told AFP.

More than 68,000 refugees have been registered entering Macedonia since the beginning of the year, and police say they stopped about 4,000 people trying to cross illegally in January alone.

The European Commission last month pledged to increase security at the Greek-Macedonian frontier, where there are currently more than 60 police officers from other countries to help control the influx.

Recently Macedonia has intermittently closed the border to refugees and it is now allowing across only those wishing to go to Germany or Austria, following similar decisions further along the migrant trail.

Macedonian Foreign Minister Nikola Poposki said in January that his government had no intention to fully close the border, but would coordinate with the European Union and ‘do whatever necessary’ to help solve the crisis.

The new fence will be at a distance of five metres (16 feet) from the one erected in November on both sides of the border crossing for refugees at Gevgelija, the army official said.

He refused to say how long the new fence would be, but local media reported that it would stretch for more than 30 kilometres (19 miles) along the frontier.

Lence Zdravkin, an aid worker in Gevgelija, told AFP by telephone that the situation had become ‘a bit tense’ since authorities began building the new fence.

Meanwhile Austrian Foreign Minister Sebastian Kurz, on a visit to Sarajevo, praised Macedonia for its efforts to slow down the flow of people, adding that the Greek government ‘did not help much in this area’.

‘We want to make it easier for Macedonia and support it as well as other countries because they are not capable of stopping the migrant crisis on their own,’ Kurz told reporters.

Twenty-four migrants, including 11 children, drowned in the Aegean Sea on Monday as they tried to cross from Turkey to Greece, a Turkish news agency said, following the deaths of more than 360 in the Mediterranean in January.

Bulgarian authorities said Sunday that two female migrants found dead in a rural mountainous region of the country had died due to freezing conditions.