Spain's King Felipe VI is set to visit his royal counterpart in Saudi Arabia on Saturday as the two countries near finalizing a $2.1 billion deal that will see Spain send warships to Riyadh, despite human rights concerns, Agence France Press reported.

Felipe, whose father and predecessor Juan Carlos was close to the Saudi royal family, was personally invited last year by Saudi King Salman bin Abdulaziz al-Saud. The trip had been postponed twice before due to a new Spanish government being formed and the death of Saudi defense minister Turki bin Abdulaziz al-Saud, according to Kuwait News Agency. Felipe is scheduled to meet with top royal family members and other political officials during the monarch's three-day visit, which Spanish media has associated with the multi-billion-dollar military deal for Avante warships made by Spanish ship maker Navantia.

"We can only confirm that negotiations are very advanced to build five warships which would be sold to the Saudi navy," a spokesperson for Navantia told AFP.

Human rights groups have come out against the deal, which would bolster a Saudi Arabia military force that has been active in Yemen. Riyadh intervened in its southern neighbor's conflict when the Houthis, a rebel movement representing the country's Zaidi Shiite minority, ousted now-exiled President Abbed Rabbo Hadi from Sana'a. Fearing a connection between its Shiite regional rival Iran and the Houthis, Saudi Arabia launched a military campaign in 2015 to counter the movement's growing influence in Yemen, one of the poorest countries in the Middle East.

The U.N. accused Saudi Arabia of being responsible for over 2,200 civilians deaths and the displacement of many more in Yemen. Saudi Arabia's role has even caused the United States, one of its closest allies, to scale back military support for the oil-rich Gulf kingdom. International human rights organizations Greenpeace, Oxfam and Amnesty International were among the groups that sent letters to the Spanish government urging it to reconsider the sale. Alberto Estevez, an arms sales expert at Amnesty International's Spanish branch, called the warship deal "clearly illegal."

Felipe's father, Carlos, was a frequent guest of the Saudi royal house in his final years as ruling monarch, visiting the country five times between 2006 and 2014. His close relations reportedly helped a Spanish company win a contract in 2011 to develop a $7 billion high-speed railway between Islam's holiest cities of Mecca and Medina in Saudi Arabia. Spain's military ties to Saudi Arabia have since increased as the fourth-biggest exporter of arms to Riyadh.