"It's difficult to see any early break or any early lessening of this gradual tightening of the encirclement of Sarajevo," Mr Akashi said. He added that Lieutenant-General Rupert Smith, the UN commander in Bosnia, met Radovan Karadzic, the Bosnian Serb leader, on Tuesday, "and the Serb attitude was very stern".
Eight people were injured by sniper and mortar fire in Sarajevo yesterday. On Monday, Mr Akashi rejected General Smith's request for Nato air strikes in retaliation for Serbian shelling of the city on Sunday, saying it might worsen tension in Croatia. The shells killed 11 people and landed close to the mouth of a tunnel under Sarajevo airport - the only non-UN route for goods into the city. The attack marked a turning-point for the Bosnian Serbs. Until now, they have allowed the tunnel to operate freely.
Intense artillery exchanges have closed the vital Brcko corridor that connects Serbia, northern Bosnia and Serb-held Croatia. Serbs fired at least 1,300 shells and possibly rockets in two spells into the Croat- held Orasje pocket, just north of the corridor, a UN spokesman said. Bosnian Croat forces fired back with 38 rockets, another spokesman said in Zagreb, adding that the shells fired by the Bosnian Serbs were "innumerable" and the situation was "very serious".
A UN officer, Lieutenant-Colonel Franck Verstappen, speaking in Otok, in eastern Croatia, called it the heaviest fighting in the Brcko corridor in six months. The town of Brcko dominates the corridor. So vital is the strip to the Serbs that they call it the "corridor of life." Serbs also shot down a Bosnian army helicopter over Muslim-controlled territory in eastern Bosnia, killing 12 passengers.
The strangulation of Sarajevo has worsened as the Bosnian and Croatian Serbs suffer military reverses. Flights have been suspended for a month, and the Serbs have targeted the only road into the city, a winding track over Mount Igman, which is at the mercy of Serbian fire. The 10-minute drive is a heart-stopping race against gunners in the Serb-held suburb of Ilidza. Now, the Serbs have threatened also to target cars driving into the city across the airport.
The UN is trapped between its mandate, to deliver aid and protect the six "safe areas", and a lack of international will to help the peace- keepers enforce the mandate.
"We need a serious debate on what people expect of us," said Colum Murphy, a UN spokesman, in Sarajevo.
Mr Akashi would not be drawn on the specifics of tomorrow's meeting. But in Sarajevo, Mr Murphy said: "We will ask: 'Will you please clarify your past decisions and present intentions?' "
The five-nation Contact Group, which meets in London tomorrow, is confused over how to proceed in the nine months since the Bosnian Serbs rejected its peace plan. General Smith is known to be concerned about the lack of political leadership. Mr Murphy said the general, who is also going to Paris, will tell the Secretary-General: "If you want me to do something specific, give me the capability."