Border issues are straining ties between Pakistan and Afghanistan, sorely testing what would otherwise be close relations between the Muslim nations.

Stretching some 2,500 kilometers [1,500 miles], the Afghan-Pakistani frontier is a troubled place these days.

Border security is first and foremost on the mind of Afghanistan's fledgling transitional government.

Afghanistan's eastern and southern provinces suffer from an insurgency waged by militants loyal to the country's former Taleban regime.

Taleban fighters, along with militants from the al-Qaida terrorist organization and renegade local militias, stage frequent attacks against Afghan targets, including police and aid workers. U.S. troops, deployed in the area to help combat the insurgency, also regularly come under attack.

According to Afghan officials, the militants are receiving aid and refuge on the Pakistani side of the border, crossing over to Afghanistan to commit attacks, and then fleeing back across the frontier.

Top advisor to the Afghan Interior Ministry, Shahmahmood Miakhel, says the government of Pakistan is not doing enough to seal its border.

"Terrorist organizations use the other side of the border for logistic purposes," said Mr. Miakhel. "Our concern is that the government of Pakistan should do their best to stop these things from their side, and we also do our best too."

After months of criticism from Afghanistan, the Pakistanis are trying to prove they are doing their part.

Pakistan's army has for the first time in its history deployed in large numbers in the country's semi-autonomous tribal areas.

They have also staged high-profile operations against suspected insurgents, including a major offensive on October 2, which resulted in the deaths of eight alleged al-Qaida members and the arrest of 18 others.

But security is not the only problem on the Afghan-Pakistan border. Disputes are now arising over the location and very legitimacy of the boundary.

With border markings between the two sides rare, Pakistani and Afghan border forces engaged in a series of skirmishes earlier this year, with each side claiming the other had encroached on its territory.

Top Pakistan army Spokesman Major General Shaukat Sultan Khan says those incidents involved misunderstandings that have since been cleared up.

"As regards to those reported clashes in the media, I would say, they were not really clashes that way," said Major General Khan. "There might be some misunderstanding at the lower level, but there wasn't any kind of misunderstanding at the higher level."

No such skirmishes have been reported for several months, both sides say, and a joint commission of Pakistani, Afghan and U.S. officials has been working to clarify demarcation issues. They are expected to issue a report in mid-November.

But even a clearly marked boundary may not solve the problem.

Some community leaders of Afghanistan's largest ethnic group, the Pashtuns, say the frontier drawn up over a century ago by the British should be redrawn to include Pakistan's Pashtun-majority areas as part of a "greater Afghanistan."

Pakistan says redrawing the border is out of the question. Afghan President Hamid Karzai has refused to speak about the issue for the time being.

"It's something for the Afghan people to decide," he said. "This government is a transitional government. It cannot talk about things like that."

But political commentator Talat Masood, a former high-ranking Pakistani general, says the question is a rhetorical one, used only for leveraging negotiations on other, more important issues.

"From our point of view, and from most of the Afghans' point of view, it is a closed issue," said Mr. Masood. "But sometimes, this is raised to create problems."

Supporters of the current boundary point out that few Pakistani Pashtuns would be interested in seeing their cities and villages become part of comparatively poorer Afghanistan.