Abuja - Nigeria's new government was warned against waste and lawlessness on meeting President Muhammadu Buhari on Thursday for the first time as a group since the ministers' nominations were confirmed.
The 36 ministers-designate were spending two days at a "retreat", with an announcement expected soon over which government departments they will be assigned and their formal inauguration.
Buhari, who was elected on a promise to root out endemic corruption, has been criticised for taking nearly five months to put together his senior ministerial team.
Names were finally submitted at the end of September but final approval from the Senate was not secured until last week.
"The need for observing the rule of law is being emphasised to ensure that impunity is removed from government conduct," Buhari told the group before the meeting.
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"It is expected that we make the running of government at all levels as lean as possible, avoid waste and conserve resources."
Nigeria's constitution stipulates that ministers must come from each of the 36 states of the federation but Buhari has been thought to want to slim down the number of ministries.
He has also hinted that not all the successful nominees will be given portfolios.
Buhari, a former oil minister under Olusegun Obasanjo in the 1970s, has said he will personally take charge of the oil sector, which he is seeking to transform to cut rampant corruption and mismanagement.
But he said diversifying the economy, which depends on crude for 90 percent of foreign exchange earnings and more than 70 percent of overall government revenue, was a major priority.
Nigeria, Africa's biggest economy and number one oil producer, has been hit badly by the fall in global crude prices.
Mining and agriculture were highlighted as potential drivers of revenue and employment, he added.