Leading article: It is time for Libya's freedom fighters to grow up

That the UN should call for restraint amid the chaos in Libya is a given.

But it was nonetheless right that yesterday's release of $1.5bn worth of frozen assets should be accompanied by a condemnation of reprisals against troops loyal to the regime of Colonel Gaddafi. What was starkly missing was a similar message from Libya's Transitional National Council (TNC).

It was never going to be easy to turn a scattered coalition of freedom fighters into a coherent political authority. But with continuing fighting in Tripoli and troubling reports of summary killings, the opportunity for political leadership must not be missed.

The latest disturbing developments are not without implications for Nato. If it was tricky to justify military intervention when the rebels were plucky underdogs fighting for freedom and Gaddafi was threatening street-by-street slaughter, it will become almost impossible if a shift in the balance of power unleashes mass executions.

But the real challenge is for the TNC – and it has much ground to make up. Since last weekend, when the six-month conflict entered what is hoped will be its final phase, the TNC has struggled to live up to its billing as a government-in-waiting, ready for the task of rebuilding a country shattered by four decades of autocratic rule.

Confidence in the unity of the coalition was already shaken after last month's murder of the rebel military commander Major-General Abdel Fatah Younes, a matter that remains worryingly unexplained. Then came the much-trumpeted capture of Gaddafi's favoured successor, his son Saif al-Islam, in the initial assault on Tripoli. Within hours Saif turned up for an impromptu photocall at a hotel full of foreign journalists, adding to the sense of the rebels as at best confused, at worst outright dishonest. Now come allegations of executions in Tripoli that smack of a total breakdown in control.

The TNC has a task of awesome complexity ahead of it, and it is as well to be realistic. Despite the jubilation that accompanied the storming of Tripoli earlier in the week, the conflict may still be far from over. But the wresting of the capital from the Gaddafi regime's control is a turning point, and the TNC must grow into its new role quickly.

First, it must take concrete steps to counter concerns that the collapse of the Gaddafi regime will unleash pent-up tribal or regional rivalries. That means unequivocal calls for national unity, and the forceful condemnation of revenge attacks of any kind.

Second, although the focus of military action is shifting to Gaddafi's birthplace of Sirte – where he is suspected to be hiding – the central focus of the TNC must not shift with it. While of immense symbolic value, chasing down Gaddafi can no longer be the top priority. Securing widespread civilian support by restoring basic infrastructure in the capital, getting water supplies running and addressing food and fuel shortages is now just as important.

There are signs of progress. The move of the TNC's headquarters from Benghazi to Tripoli yesterday, for example, is a good start. But there is much to be done. And just as any boots on the ground must be Libyan, so must the imposition of the rule of law. The TNC has had a short and tempestuous apprenticeship. It is time to show that it has grown up.