The meeting between the two at Costa’s official residence in Lisbon lasted about an hour and had as its central theme, according to the Portuguese government, possible areas for cooperation in science, economics and environment.

"It was a courtesy meeting,” said the source. “They discussed bilateral relations and identified ways of cooperation in areas such as innovation, science and water."

Netanyahu had arrived in Lisbon on Wednesday, that same day holding a meeting with the US secretary of state, Mike Pompeo. Afterwards, the Israeli prime minister praised the US decision to impose fresh sanctions on Iran and argued that the resulting financial pressure represented a protest against Tehran's growing influence in the Middle East.

Netanyahu said that Iran was the first, second and third issue to be discussed.

"As we speak, Iran is increasing its aggression," he said. "We are actively involved in countering this aggression."

Israel sees Iran as its main enemy because of the involvement of the regime in Tehran in neighbouring Syria and in supporting militant groups in the Middle East and Persian Gulf. Israel also accuses Iran of wanting to develop a nuclear bomb – something Iran denies.

The meeting between Pompeo and Netanyahu caused some political controversy in Portugal. The country’s president, Marcelo Rebelo de Sousa, sought to play it down, tellingn reports that it was not a concern for him as head of state.

"It was a meeting between politicians from these two countries who chose Portuguese territory to meet," he said, during a visit to a school in Vila do Conde, in Porto district.

Later, he stressed that this was "not the first time leaders from other countries have chosen Portugal to meet".