Uwe Corsepius, EU Council's secretary general

UPDATE: According to a British official, the UK has today been invited to participate in the treaty negotiations, a significant shift that will allow London to weigh in on some of the most sensitive issues to be discussed, including whether EU institutions will enforce the new pact.

Senior officials from European national finance ministries chatted last night in the first informal negotiations on the highly-touted new intergovernmental treaty to govern the region’s economic policy, though diplomats say little substance was discussed.

Ahead of the talks, however, Uwe Corsepius, the new secretary general of the European Council, sent out a four-page letter to negotiators in an attempt to set a roadmap for how the talks will proceed – and we at Brussels Blog got our mitts on it.

Significantly, Corsepius writes that he wants negotiations completed by the end of January “so as to allow the signature of the agreement at the beginning of March”. Officials said this is why a new informal EU summit is tentatively scheduled for early February. A first draft of the treaty text could be done by tomorrow, or early next week at the latest.

Finland's Jyrki Katainen, France's Nicolas Sarkozy, Germany's Angela Merkel and EU Commission's José Manuel Barroso at last week's summit.

This morning, we are fronting our newspaper with a story led by fellow Brussels Blogger Joshua Chaffin about the growing problems in multiple European capitals — not just London — with the nascent  economic convergence treaty agreed to at last week’s summit.

That story was written with a lot of help from our network of correspondents across Europe, and given space constraints in the dead-tree version of our report, we weren’t able to go into all the detailed accounts we got from our FT colleagues. Here on the blog, we thought we’d provide a more in-depth taste of the potential hiccups ahead.