ROME (REUTERS) - The ancient city of Pompeii was off limits to the public on Friday morning and Rome's Colosseum temporarily closed on Thursday amid a rumbling dispute between Italy's Culture Ministry and workers.

Tourists hoping to see the ancient city long-preserved under volcanic ash or the amphitheatre where gladiators fought - two of Italy's most popular archaeological sites - had to wait outside while unions met to discuss staff shortages and alleged payment delays.

Three years of recession have further strained Italy's capacity to protect a vast cultural wealth which has already suffered decades of mismanagement and bureaucracy.

Culture Minister Dario Franceschini has launched a reorganisation which he says will make the department more modern and efficient, but unions say it will create confusion and fail to solve the problem of insufficient funding.

"The difficulties are increasing everywhere, with worsening endemic problems, a lack of resources and serious understaffing made even more intolerable - if that is possible - by chaos following the reorganisation," the FLP BAC union said in a statement.

Franceschini, whose reforms include hiring new museum managers through an international head-hunt and giving tax breaks for donors to cultural causes, decried the temporary closure at Pompeii.

"Another surprise union meeting at Pompeii and tourists queuing up in the sun. This is the way to damage unions, workers' rights and our own country," he said on Twitter.

Both sites reopened after a few hours when the union meetings finished.