KABUL - Afghan Interior Minister Noor-ul-Haq Olomi has offered his resignation to President Ashraf Ghani after mounting criticism of the worsening security situation over recent months, people familiar with the matter said.

The resignation offer, which the sources said had not yet been accepted, deals a further blow to Ghani's struggling government, which is without a permanent defence minister and which recently lost the head of its intelligence service just as the Taliban has stepped up its insurgency. It also highlights the deep fractures in the national unity government which gave Ghani and Chief Executive Abdullah Abdullah, the two rival candidates in the disputed election of 2014, a share in power.

Three separate government and diplomatic sources, who spoke on condition of anonymity, said Olomi had offered his resignation but that Ghani was still considering a replacement before accepting it. Asked whether Olomi had offered his resignation, Ghani's deputy spokesman Sayed Zafar Hashemi said: "Bringing reform to government entitities, including the ministry of the interior, to increase efficiency has been a government priority."

An interior ministry spokesman said he could not confirm the information. One senior official said Ghani was meeting Chief Executive Abdullah, who nominated Olomi to the ministry and who would be consulted before any replacement can be appointed. The move comes as officials from Afghanistan, Pakistan, the United States and China are meeting in Islamabad to try to lay the ground for a resumption of peace talks with the Taliban.

Speculation over the future of Olomi had been swirling for months after he survived moves by a group of members of parliament in November to launch a no confidence motion against him over the deteriorating security outlook. The Taliban have stepped up their insurgency since the withdrawal of most foreign troops in 2014, briefly seizing the northern city of Kunduz last year and mounting a series of deadly suicide attacks in the capital Kabul.

According to the Special Inspector General for Afghanistan Reconstruction, a U.S. Congressional oversight body, the Islamist insurgents now control more territory than at any time since 2001, when the Taliban was driven from power by U.S.-led forces in the wake of the Sept. 11 attacks in New York. At the same time, the government has been hobbled by political infighting, which has prevented the appointment of a permanent defence minister for more than a year.

Disagreements over the approach to dealing with the insurgency also prompted the powerful head of the National Directorate for Security, Rahmatullah Nabil to walk out of the job in December.