After visiting a makeshift camp in the Greek port of Piraeus on Wednesday, Hollywood star Angelina Jolie said refugees were stuck in a "deteriorating humanitarian situation" and needed help.

The 40-year-old actress, who also works as a UNHCR goodwill ambassador, spent around 30 minutes at the port, speaking to UN staff and refugees. During that time, she directed much of her attention to the plight of children, listening to their stories and taking pictures with them.

As she left, dozens of refugees chanted "Skopje, open the borders" in a reference to the former Yugoslav Republic of Macedonia barring passage to migrants last week, a move that was soon followed by other states along the so-called Balkan route.

Bichal, a 23-year-old Syrian woman from Aleppo, told the Agence France news agency that she hoped Jolie's presence in Greece would "do something to help open the border."

"I've been in Greece for a month and I'm still waiting to cross the border and go to Germany," she said.

Bichal is far from alone in her aspiration. Some 4,000 people are currently stuck in terminals and tents in Piraeus, only a fraction of the people stranded in Greece after the Balkan route was closed off by national border controls.

Possible visit to Idomeni

Jolie later met with Greek Prime Minister Alexis Tsipras, who told her there were "30,000 people trapped on the Greek mainland because of unilateral actions by the countries on the Balkan route."

The situation continues to be particularly dire in the border town of Idomeni, where more than 14,000 people are living in squalor. It wasn't clear whether Jolie would visit the infamous border camp on Thursday, ahead of a European Union summit with Turkey over the migrant crisis.

Jolie visited Syrian refugee camps in Lebanon on Tuesday, where she appealed to governments around the world to step up their assistance to the nearly 5 million people who have been forced by war to flee their country.

"We should never forget that for all the focus on the refugee situation in Europe at this time, the greatest pressure is still being felt in the Middle East and North Africa, as it has for each of the last five years," she said.

Rescue efforts in the Mediterranean

Despite closed-off migration routes, refugees continue to embark on perilous journeys across the Mediterranean Sea in hope of a better life in Europe. In the past few days German and Italian coast guard ships have saved the lives of more than 3,000 people.

The majority of the refugees were taken to the Italian port of Pozzallo to be processed and evaluated for asylum. Many reportedly came from Libya, a country in chaos since the toppling of Libyan leader Muammar Gaddafi in 2011 and the rise of the self-styled "Islamic State." However, there were also migrants from Sudan, Egypt, Syria, Morocco, Ethiopia, Gambia, Nigeria, Chad, Senegal and the Palestinian Territories among those saved.

According to numbers provided by the German military, more than 12,000 migrants have been rescued in Mediterranean waters since May 2015.