Labour faces accusations of overcentralised meddling after the party’s national executive vetoed planned coalitions with the Liberal Democrats or Greens in a series of formerly Conservative-held local authorities. While it is longstanding Labour policy that local parties need a green light from the national executive committee (NEC) before forming coalitions, some activists say attempts to block deals risk allowing Conservatives to regain control instead. In one council, Hertsmere, just north of London, where the Tories lost power for the first time since 1999 in this month’s elections, Labour councillors are threatening to sit as independents if the NEC continues to veto a deal with the Lib Dems. “This has been a Tory area for the last 24 years, and we’ve worked so hard to change that,” one local Labour source in the Hertfordshire district said. “It’s quite insulting now to be told we can’t get the benefits.” A similar stalemate at Cherwell council in Oxfordshire, where the NEC is refusing to allow the Labour group to govern with the Lib Dems and Greens, has prompted speculation it could end up returning to Tory control. There have been similar vetoes at two other formerly Conservative-run local authorities that are now in no overall control, Lewes in East Sussex and Canterbury in Kent. Several local Labour sources told the Guardian they believed the party was being overly rigid and interventionist. It comes after the NEC announced it would appoint the next leader of Birmingham council, following an internal report that said the Labour group was riven by factions. In a notably positive set of local election results on 4 May, Labour won control of 22 new councils, with a further 12 shifting to no overall control, many having previously been Conservative-run. Among the latter group was Hertsmere, where from the Tories’ pre-election position of holding 29 of the 39 council seats they plummeted to 16, fewer than the combined total of 14 for Labour and nine Lib Dems. But plans for a Labour-Lib Dem coalition are in deadlock after the NEC vetoed it over apparent claims about a pre-election pact between the parties, something rejected by local Labour sources. A number of Labour councillors are understood to be considering resigning from the party to sit as independents if the NEC does not back down. In Cherwell, formerly the last Conservative-run council in Oxfordshire, the Tories’ post-election total of 20 councillors is fewer than the 12 for Labour, 10 Lib Dems and three Greens. But plans for a coalition are at a stalemate after the NEC refused to allow the local Labour party to sign up to a deal with both the Lib Dems and Greens. A Labour source said the party’s policy was to make pacts with the fewest number of parties needed to form a majority. The complication in Cherwell is that the Lib Dems and Greens, as well as one independent councillor, are grouped into the so-called Progressive Oxfordshire Alliance, and so will not accept the NEC’s insistence on a Lib Dem-only deal. A first meeting of the new council removed the existing Tory leader but could not agree a replacement. One council source said that if the NEC did not back down the Conservatives might govern as a minority: “The Tories in charge again isn’t what people voted for, but there has to be an administration at some point.” In Lewes, the Greens, who became the biggest party after an election in which the Tories were wiped out, say their plans for an all-party administration involving both the Lib Dems and Labour had reached agreement but was blocked by Labour’s NEC. Labour councillors in Canterbury, where they are the biggest party, have been allowed to govern with the Lib Dems, but the NEC stopped the participation of the Greens. Neal Lawson, the head of the cross-party campaign group Compass, called for the party to show more flexibility. He said: “No Labour councillors should be blocked from forming anti-Tory alliances. Protecting the interests of local voters must come before party tribalism.”