Spanish broadcaster Sexta cited the Spanish police as saying that a parcel, presumably with explosives, was found at the US Embassy in Madrid and the building was cordoned off. 

According to Sexta, the envelope found at the US embassy is "similar" to parcels that were previously found in the country. Bomb disposal unit Tedax and other police units are working at the scene, the broadcaster said.

Earlier, the Russian Embassy in Spain condemned any threats and terrorist acts.

Spanish PM received letter similar to one which exploded at Ukraine embassy

In the same context, Spanish officials said on Thursday that Spanish Prime Minister Pedro Sanchez received a booby-trapped letter last week which was "similar" to one which exploded Wednesday at Ukraine's Embassy in Madrid, lightly injuring an employee.

Security staff carried out a "controlled explosion" of the mailed item, whose "content was similar" to that found in other letters sent to the Ukrainian embassy, an air force base, the Defense Ministry, and a military equipment firm. 

The Spanish Interior Ministry said the envelope, "containing pyrotechnic material" and addressed to Socialist Prime Minister Pedro Sanchez, arrived by regular mail on November 24.

On Wednesday, the security officer at Ukraine's Embassy in Madrid lightly injured his hand while opening a letter bomb addressed to the Ukrainian Ambassador, prompting Kiev to boost security at its embassies worldwide.

Spain's High Court has opened a probe for a possible case of terrorism.

Later in the evening, a second "suspicious postal shipment" was intercepted at the headquarters of military equipment firm Instalaza in the northeastern city of Zaragoza, the Interior Ministry pointed out. Experts carried out a controlled explosion of that mailed item as well.

Instalaza makes the grenade launchers that Spain provides to Ukrainian forces.

Earlier Thursday, security forces also detected a "suspect envelope" at an air base in Torrejon de Ardoz outside of Madrid, which is regularly used to send weapons to Ukraine.

Police were called to the base "to secure the area and investigators are analyzing this envelope," which was addressed to the base's satellite center, the Interior Ministry said.

In a statement, the Spanish Ministry explained that "both the characteristics of the envelopes and their content are similar in the four cases," adding that police had informed the National Court of the four incidents.

A Defense Ministry source told AFP that a fifth envelope with an "explosive" arrived at the Ministry in Madrid on Thursday morning, adding that experts blew up the package.

Ukraine's Ambassador to Spain, Serhii Pohoreltsev, accused Russia of the letter bomb that arrived at the Embassy.

"We are well aware of the terrorist methods of the aggressor country," Pohoreltsev said during an interview late Wednesday with Spanish public television.

"Russia's methods and attacks require us to be ready for any kind of incident, provocation, or attack," he added.

Ukrainian Foreign Minister Dmytro Kuleba ordered the strengthening of security at all Ukrainian embassies, Ukraine's Foreign Ministry spokesperson confirmed on Wednesday after the letter bomb went off at the Embassy in Madrid.

It is noteworthy that in addition to sending arms to Ukraine, Spain is training Ukrainian troops as part of a European Union program.

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