Afghan leader Hamid Karzai has postponed
a landmark visit to Pakistan due to the war in Iraq.
President Karzai was to have been the guest of honour at Pakistan's National Day parade on Sunday.
Pakistan has recently pledged millions of dollars in aid to Afghanistan
Presidential spokesman Fzal Akbar said the last-minute change of plan was due to the intensification of hostilities. The trip will now be rescheduled.
Asked whether security concerns played a part, officials say it was a possible factor.
After calling for a political solution to the crisis, the Afghan Government is now supporting military intervention in Iraq but has called on Washington and its allies to minimise civilian casualties.
However, many Afghans are opposed to the war and see it as an attack on fellow Muslims.
Others fear that their country's needs will be forgotten as the world focuses on Iraq.
The BBC's correspondent in Kabul, Catherine Davis, says that among security officials and the international community in Kabul there is concern that some forces might use the war as an opportunity to try to destabilise the country.
Diplomatic relations between Islamabad and President Karzai's government have been improving, but suspicions remain.
While Pakistan backed the former Taleban regime, a number of senior Afghan officials fought against it.
Our correspondent says that these days, the talk is of friendship and collaboration.
There are about 1.5 million Afghan refugees in Pakistan
There are already significant trade and business ties between the two neighbours.
Afghan bazaars are full of imports from Pakistan and brightly-painted Pakistani trucks are a common sight on Afghan roads.
Islamabad has offered to help Afghanistan rebuild itself.
It has announced that special facilities are being set up at the port city of Karachi.
One issue yet to be resolved is the presence of some 1.5 million Afghan refugees in Pakistan.
Security is another important topic. Both countries are helping the United States in its hunt for remnants of the Taleban and al-Qaeda in their remote border regions.