The Spanish prime minister, Mariano Rajoy, described Gibraltar’s status as an “anachronism” in a speech before the United Nations general assembly, in the latest salvo over the contested British territory.

Speaking on Wednesday night, Rajoy said: “This anachronism continues to cause inconvenience to the citizens of Gibraltar,” as well as to those Spaniards who live on the other side of the border.

Rajoy accused Britain of disregarding the process of decolonisation approved by the UN in the 1960s and called for dialogue with London.

Rajoy’s speech came shortly after officials from the European commission completed a one-day visit to Gibraltar to inspect border controls. The EC team went following complaints that Spanish border officials were causing lines of traffic to build up, making daily life a misery for people either side of the border.

The six-person EC team carried out a “technical fact-finding mission” on both sides of the border, interviewing residents and inspecting immigration and customs procedures.

The increased security on the Spanish side came after a dispute with the UK this summer over an artificial underwater reef. Gibraltar’s government dropped 74 concrete blocks into the sea in a disputed area of water regularly used by Spanish fishing boats. Gibraltar described the artificial reef as a necessary environmental protection, but the Spanish government saw it as an act of provocation. The dispute simmered all summer, leading to the intervention by the EC.

The Spanish foreign minister, Jorge Fernández Díaz, on Wednesday reiterated the claim that Gibraltar “was not working with Spain to tackle the illegal smuggling of tobacco”, and other illegal activities, and that Spain had no choice but “to increase controls on the border, which is causing the extra-long queues”.

In a statement, the government of Gibraltar accused Fernández of talking “complete nonsense … [he] should know better than to make factually incorrect statements of this kind. The reality is that the laws against tobacco smuggling are tougher in Gibraltar than they are in Spain itself. The reality is that Gibraltar has transposed, implemented and fully complies with all EU directives against money laundering.”

The EC team consisted of officials from the department of home affairs, customs union and justice, as well as the European anti-fraud office (Olaf), investigating allegations from Spain that Gibraltar is a haven for smuggling of illegal contraband, particularly cheap cigarettes.

In the runup to Wednesday’s visit, Gibraltar accused Spain of ordering a last-minute improvement to its traffic control system to disguise the delays they had caused.

“This crude attempt at the last minute by the Spanish authorities to disguise and conceal the way in which they normally conduct such searches at the border, in a manner that is likely to mislead the European commission, will be brought to the immediate attention of the EC,” said a spokesman for the Gibraltar government.

“Clearly, it would seem that the announcement of the European commission’s visit is already producing positive effects, even before the commission inspectors arrive.”

Last month, there were reports of violence at the border as tempers frayed while angry commuters queued to get home. As well as reports of missiles being thrown at the Spanish Guardia Civil officers, two unions organised a protest after it was alleged that an officer was injured when a Gibraltar-registered car failed to stop.

Around 8,000 Spaniards are thought to work in Gibraltar but live in Spain, mostly in the border towns of La Línea and Algeciras.

The Guardian