Fears that Azerbaijan has systematically destroyed hundreds of 500-year-old Christian artefacts have exploded into a diplomatic row, after Euro MPs were barred from inspecting an ancient Armenian burial site.

The predominantly Muslim country's government has been accused of "flagrant vandalism" similar to the Taliban's demolition of the Bamiyan Buddhas in Afghanistan.

The claims centre on the fate of rare "khachkars", stone crosses carved with intricate floral designs, at the burial ground of Djulfa in the Nakhichevan region of Azerbaijan, an enclave separated from the rest of the country by Armenia.

The works - some of the most important examples of Armenian heritage - are said to have been smashed with sledgehammers last December as the site was concreted over.

The Azerbaijan government, which denies the claims, is now at the centre of a row with MEPs, some of whom it accused of a "biased and hysterical approach". Its ambassador to the EU also says the European Parliament has ignored damage to Muslim sites in Armenia. Azerbaijan has refused to allow a delegation of Euro MPs permission to visit the 1,500-year-old Djulfa cemetery during their trip to the region last month.

Most of original 10,000 khachkars, most of which date from the 15th and 16th century, were destroyed by the early 20th century, leaving probably fewer than 3,000 by the late 1970s.

According to the International Council on Monuments and Sites (Icomos), the Azerbaijan government removed 800 khachkars in 1998. Though the destruction was halted following protests from Unesco, it resumed four years later. By January 2003 "the 1,500-year-old cemetery had completely been flattened," Icomos says. Witnesses, quoted in the Armenian press, say the final round of vandalism was unleashed in December last year by Azerbaijani soldiers wielding sledgehammers.

The president of Icomos, Michael Petzet, said: "Now that all traces of this highly important historic site seem to have been extinguished all we can do is mourn the loss and protest against this totally senseless destruction."

Some MEPs believe that, boosted by its oil revenues, Azerbaijan is adopting an increasingly assertive stance in the region. Charles Tannock, Conservative foreign affairs spokesman in the European parliament, argued: "This is very similar to the Buddha statues destroyed by the Taliban. They have concreted the area over and turned it into a military camp. If they have nothing to hide then we should be allowed to inspect the terrain."

When MEPs passed a critical resolution in February, Azerbaijan's Foreign Minister, Elmar Mammadyarov, made a formal protest. Then, when the parliament's delegation for relations with Armenia, Azerbaijan and Georgia, asked to combine a mission to Armenia with a visit to the Djulfa archaeological site, their request was refused. The Council of Europe's Parliamentary Assembly hopes to visit the site and its secretary general has offered to set up an expert group to examine cultural sites in Azerbaijan and Armenia. MEPs insist that the authorities in Azerbaijan should open their doors if they have nothing to hide.

Hannes Swoboda, an Austrian socialist MEP and member of the committee barred from examining the site, said he hopes a visit can be arranged in the autumn.

He added: "If they do not allow us to go, we have a clear hint that something bad has happened. If something is hidden we want to ask why. It can only be because some of the allegations are true." And he warned: "One of the major elements of any country that wants to come close to Europe is that the cultural heritage of neighbours is respected."