EU president Herman Van Rompuy on Thursday issued a damning report card on bloc efforts to complete the single European market, in a summit invitation that appeared to echo criticism made by British Prime Minister David Cameron. In his letter to leaders, seven days ahead of a two-day summit in Brussels, Van Rompuy said an end-2012 deadline to turbo-charge the single market was lamentably missed. Britain joined what was then known as the European Economic Community after a 1973 referendum, but has repeatedly complained that many barriers still need breaking down -- and Van Rompuy agreed. "Regrettably, the deadline we set was missed for a number of (priorities) ... in fact, for most of them," Van Rompuy said of 12 areas targeted for cross-border integration that Brussels maintains could generate millions of jobs at a time of record-high unemployment. "This delay is hard to justify, since it casts doubt on our resolve to urgently take all the concrete steps to bring back growth to the European economy," read the formal summit invitation letter. Summit chairman Van Rompuy said that national governments must show "more flexibility" during negotiations and "more willingness to compromise." "I appeal to you to muster sufficient political will to close these negotiations as early as possible this year, as a matter of urgency," he said of the creation of genuinely cross-border infrastructure networks in energy, transport and telecoms. Many of these areas however face spending cuts in the EU's budget for the rest of the decade. Nonetheless, Cameron, who is often isolated in EU policymaking, and conservative backers have argued that these represent the most reliable engine for growth -- and have increasingly painted this focus as the EU's raison d'etre. Van Rompuy said a summit in May, for instance, would be re-focused on the key energy market. The EU imports most of its gas needs, for instance, while electricity production and consumption from north to south are considered massively un-matched. This change in tack after three years in crisis-fighting mode comes as internal EU papers show that top officials in Van Rompuy's private office now consider publicly-lauded initiatives such as a "Banking Union" are fast "losing pace." The banking union was intended to close off the vicious circle of sovereign and banking debt since Greece emerged as the weak link in the euro currency chain, but has consistently fallen foul of vested national interests and resistance in Europe's top finance centre, the City of London. As EU leaders of different political hues battle over the need to maintain austerity despite concerns over the social fallout, European Commission head Jose Manuel Barroso also tried to nudge the debate in a separate speech Thursday. "There are some in Europe that only speak about solidarity forgetting the need to show responsibility," he said. "Others always remind us about responsibility, forgetting the need to show solidarity. "It is not a question of choosing between solidarity and responsibility -- both are needed," he insisted. Diplomats, meanwhile, confirmed that the talks will see leaders separate into a eurozone-only format for a night-time session during the March 14-15 meeting, ahead of discussions mainly focused on the EU's relations with Russia on the second day.