Homeland Security Secretary Janet Napolitano spoke with officials Saturday about ways to stop terrorists from transporting bomb-making chemicals across the Afghanistan-Pakistan border during a meeting with Afghan President Hamid Karzai and other members of his administration. 

Napolitano's agency has about two dozen customs and border officials in the war-torn country, with more on the way, many training Afghan forces. The nation's emerging security force is tasked with patrolling a porous border with Pakistan where Taliban fighters and Islamic extremists cross freely, along with opium and materials used to manufacture improvised-explosive devices. 

Napolitano, who landed in Afghanistan on New Year's Eve on an unannounced visit, talked about how the two countries could work together to better intercept this trafficking during the meeting with Karzai and Finance Minister Omar Zakhiwal on Saturday. She said in a written statement that civilian officials in her department have made "significant progress" in working with Afghan officers toward disrupting Al Qaeda operations along the border. 

Click here to see video of Napolitano's meeting with Karzai

Napolitano also said 52 former U.S. customs and border patrol officers would arrive in Afghanistan in 2011, to complement the 25 on the ground -- up from 11 a year ago. 

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The secretary will also meet with the interior minister before leaving for Qatar later in the weekend. 

Karzai's office said in a statement that during their talks, Napolitano said the United States would help Afghanistan with equipment and capacity building for the country's customs operations and with the training of border police. 

Karzai told the visiting secretary that the Afghan side was trying to strengthen its capacity and that the country would be able to assume responsibility for security in four years' time, when international combat troops are expected to hand over to Afghan security forces. 

It will be difficult, however, to train enough Afghan border police and agents to control the porous border. For the past year, Napolitano's department has been working with the Afghan government to establish a border security and customs system and crack down on the smuggling of drugs and cash. 

Halting the flow of billions of dollars of cash from Afghanistan is a top U.S. priority. Since 2007, an estimated $3 billion in cash has flowed out of Afghanistan through the country's two major airports, most of it to Dubai, according to Afghan police and intelligence officials. 

Zakhilwal's office said in a statement he and Napolitano discussed the cash-flow issue and that an action plan to address it was deemed "as necessary." The statement did not elaborate on what steps might be taken. But the ministry said the U.S. has been providing assistance to better organize the network of money transfer enterprises -- commonly known as hawalas -- and improving the way in which cash transfers are regulated and tracked. 

While taking large amounts of money is not illegal under Afghan law, the scope of the transfers has alarmed U.S. and other international officials because it could be aid funds that have been diverted, drug money or Taliban cash. 

Hawalas, in particular, have been a source of concern for the U.S. since the transfers are largely untraceable and officials worry that the systems are used to funnel money across Afghanistan and elsewhere in the Muslim world to militants. 

Napolitano said training border police and customs officials was an important part of NATO's overall aim to transition security to Afghan forces by the end of 2014 -- when most foreign combat troops are expected to leave the country. 

In southern Afghanistan, the U.S.-led coalition said one of its service members was killed by a bomb -- the first to die in the new year. It did not provide details. 

Last year was by far the deadliest for foreign troops in the decade-old war, with 702 killed, eclipsing the 2009 record of 504. 

NATO also said it killed at least eight insurgents and captured a Taliban leader in several operations throughout Afghanistan. It was unclear whether the Taliban leader was killed or detained. 

The Associated Press contributed to this report.