British Prime Minister Gordon Brown pledged Wednesday to send more troops to Afghanistan but only if NATO and the Afghan government do more to help fight the Taliban.

Brown said his government would increase British troop levels to 9,500 — an increase of about 500 — on the condition that President Hamid Karzai reduce corruption and improve his government's performance. Brown also pledged to send troops only if he can provide them with the proper equipment, and if NATO allies increase their contributions to the war effort.

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Military experts said Brown wants to show British support for the war as the U.S. debates an increase in its Afghan troop levels and he is unlikely to call off the deployment. Brown did not specify what contributions he is seeking from NATO nations, or exactly what the Afghans must do to get the extra forces, an indication that the conditions are largely designed to put political pressure on Karzai and NATO, they said.

The increase in British troops is small and may be of mostly symbolic importance, but it will likely be welcomed by President Barack Obama as his administration ponders difficult options in Afghanistan. These include a possible increase in U.S. forces, which now number about 67,000. Britain is the second-largest force in the 42-nation NATO coalition in Afghanistan.

Retired Col. Christopher Langton, a senior fellow at The International Institute for Strategic Studies in London, said it is extremely unlikely that Brown will ultimately decide to cancel the deployment even if the conditions he demanded are not met, in part because Brown has said he is responding to requests from senior military advisers.

Langton said, however, that Brown will have to make sure the troops are properly equipped and trained, as promised, or face tremendous public anger at home. The government has already been criticized for not providing enough body armor and heavy vehicles.

"That's the one condition he must meet," Langton said. "The others he can sort of manage."

Brown has faced conflicting pressures at home as public opinion polls show drooping support for the war and former commanders say more troops are needed fast to avoid defeat at the hand of Taliban insurgents.

Brown appeared to dismiss an argument put forward by some in the U.S. administration that Western forces should avoid raising troops levels and limit their goals to eliminating Al Qaeda through precise strikes by aerial drones and special forces.

"Our objective is clear and focused: to prevent Al Qaeda launching attacks on our streets and threatening legitimate government in Afghanistan and Pakistan," he said. "But if we limit ourselves simply to targeting Al Qaeda, without building the capacity of Afghanistan and Pakistan to deal with terrorism and violent extremism, the security gains will not endure."

Brown also said he will demand a better performance from Karzai's government.

"I asked them for an assurance that they will sign a contract with us and the other allied powers about the elimination of corruption, the proper conduct of government, the appointment of governors who can actually manage in the provinces and the appointment of junior officials who can do that as well, as well as asking them to support our forces with a proper number of Afghan forces working with them," Brown said.

He said Britain will also send $16 million in aid to Pakistan and Afghanistan. He said the fight against the Al Qaeda terrorist network cannot be confined to Afghanistan while the government of Pakistan is under threat.

It is not clear that the proposed extra deployment is large enough to have an impact on the battlefield, where Taliban loyalists have been able to plant roadside bombs with devastating impact on British troops.

Steven Bowns, a specialist at the Chatham House think tank in London, said troops will remain vulnerable on the ground until more helicopters are procured.

"They are indeed needed but it seems like a political gesture rather than a serious deployment," he said.

Brown's recently retired army chief accused him of turning down the military's request for an extra 2,000 troops, an allegation the prime minister's office denied.

Brown's supporters have questioned retired Gen. Richard Dannatt's motives, noting that he has since been picked to become a senior adviser to the opposition Conservative Party.