A team of European Union inspectors are visiting Gibraltar to investigate a border row that has caused diplomatic tensions between the UK and Spain. London and British Overseas Territory Gibraltar complained to the EU that Spain's over-zealous checks on border traffic were holding up workers and tourists. Spain accuses Gibraltar of not doing enough to combat cigarette smuggling.
The six inspectors have been interviewing people and observing immigration and customs procedures.
A group of Spanish workers who have to cross the border to get to work followed the inspectors, waving signs protesting about the border queues.
A spokesman for the group - the ASCTEG - said it would have been sensible not to announce the inspection and let the inspectors see what the queue is really like instead.
On Wednesday morning, drivers were queuing at the border for up to two hours, according to Gibraltar authorities.
Gibraltar's chief minister Fabian Picardo said he hoped the inspectors' visit would offer a solution to the situation at the border. He added he planned to provide the team with any requested documents and allow them access to all areas needed for their work, and insisted Gibraltar had nothing to hide.
Spain's interior minister Jorge Fernandez Diaz said he was convinced the team would find out the scale of tobacco smuggling taking place in Gibraltar.
He said Spain would assist the team however they could, but warned that tighter border controls would continue until the Gibraltar authorities helped to end tobacco smuggling.
The row broke out in July when Spanish authorities increased checks at the Gibraltar border, saying they were necessary to tackle tobacco smuggling.
Gibraltar, though, said the strict checks came after it dropped 74 concrete blocks into the sea next to its territory, intended to create an artificial reef and encourage sea life to flourish.
Spain said the blocks would disrupt waters used by its fishing boats, but denied that the development had prompted its increased border checks.
Britain says the border checks break EU free movement rules, and last month UK Prime Minister David Cameron told the EU Commission he had serious concerns that Spain's actions were politically motivated.
The visiting team of inspectors comes from the customs union, justice services and anti-fraud office of the European Commission, which is the EU executive arm.
They held a three-hour meeting with Gibraltar officials before inspecting the border crossing. They are expected to do the same on the Spanish side.