"This is the largest shipment made until now, more than doubling what we have sent so far," he told a joint news conference with Ukrainian President Volodymyr Zelensky and Danish Prime Minister Mette Frederiksen.

A Spanish navy ship loaded with the material departed a port in Spain on Thursday bound for Poland, from where the cargo will be transported to Ukraine, Sanchez said.

"The ship carries 30 trucks, several special heavy transport vehicles, and 10 small vehicles loaded with the military material that will be transferred to Ukraine," he added.

Sanchez and his Danish counterpart arrived in Kyiv earlier on Thursday for talks with Zelensky, the latest in a series of visits by European leaders to show their support for Ukraine.

"Shocked to witness the horror and atrocities of Putin's war on the streets of Borodyanka," Sanchez tweeted earlier on Thursday after visiting the war-ravaged town outside of Kyiv with Frederiksen.

Madrid has sent about a dozen planes to Ukraine carrying "hundreds of tonnes" of weapons and humanitarian supplies, Defence Minister Margarita Robles said on Monday.

In another sign of support for Kyiv, Sanchez announced on Monday that Spain would reopen its embassy in the Ukrainian capital "in a few days' time".

The embassy suspended activity the day after the Russian invasion on February 24 for security reasons.

Spain has also taken in 134,000 Ukrainians, of whom 64,000 have received temporary protection, including accommodation and a work permit.