Sir Suma Chakrabarti said UK aid to Iraq had been a priority
UK aid officials had "scanty" evidence of the situation in Iraq in the lead-up to the 2003 invasion, a senior civil servant has said.
Sir Suma Chakrabarti, ex-Department for International Development permanent secretary, said contact with UN staff had been banned until October 2002.
This restriction had been put in place to avoid revealing that military action was possible, he told the Iraq Inquiry.
This meant most knowledge was "desktop information" only, he said.
The UK had no diplomatic relations with Saddam Hussein's Iraq for 12 years leading up the invasion.
This ensured that on-the-ground detail of the country was not easily available to aid officials planning post-war reconstruction and development, Sir Suma said.
He told the inquiry that knowledge of Iraq was, as a result "rather scanty", adding: "Most of the analysis was desktop analysis, based on United Nations information."
He added: "At that time [mid-2002] there was a ban on contact with the NGOs [non-government organisations] in Iraq and the UN in case [the possibility of military operations was revealed]."
November-December: Former top civil servants, spy chiefs, diplomats and military commanders to give evidence
January-February 2010: Tony Blair, Gordon Brown and other politicians expected to appear before the panel
March 2010: Inquiry expected to adjourn ahead of the general election campaign
July-August 2010: Inquiry expected to resume
Report set to be published in late 2010 or early 2011
But Sir Suma said that, on 23 October 2002, Downing Street had eased the restrictions and said such discussions could take place in a "discreet" way, adding: "That was a small opening in the aperture for us."
He also said that, as the US and UK moved towards the eventual invasion of Iraq in March 2003, communication within Whitehall improved, with the Ministry of Defence working more closely with the Department for International Development [DfID].
DfID's involvement in the run-up to war has been criticised by other witnesses to the Iraq Inquiry.
Last week, Admiral Lord Boyce, former chief of the defence staff, said the International Development Secretary at the time, Clare Short, had ensured staff were "particularly uncooperative" during planning.
He said: "You had people on the ground who were excellent operators from DfID who were told to sit in a tent and not to do anything because that was the instruction they received."
Sir Suma admitted there had been "personality tensions" but added: "There was absolutely no instruction... to sit in tents."
Ms Short eventually quit over the lack of UN involvement in the reconstruction effort.
Last week, Sir Kevin Tebbit, the former top official at the Ministry of Defence, was critical of DfID's role in providing humanitarian and developmental aid to Iraq, saying it had been at odds with the rest of government.
He told the inquiry: "Their focus on poverty relief rather than backing a strategic objective of the British government meant they were not sure at first the Iraqi people were quite poor enough to deserve major DFID aid."
But Sir Suma, permanent secretary at DfID from 2002 to 2007, said: "My perspective is that is incorrect... We prioritised Iraq heavily at the Department for International Development in terms of resourcing."
He added that Iraq had been "the biggest recipient of British aid that year"  and that this "belies" Sir Kevin's point.
Sir Suma is now the permanent secretary at the Ministry of Justice.
Sir John Scarlett, former chairman of the Joint Intelligence Committee, which compiled a 2002 dossier saying Iraq would be able to deploy weapons of mass destruction "within 45 minutes", will be questioned later.
In its first few weeks, the Iraq Inquiry is hearing from senior diplomats and policy advisers who shaped policy in the run-up to the war.
The crucial question of the legality of the war will not be addressed until early next year, when Tony Blair is expected to give evidence.