TOKYO — US Secretary of State Hillary Clinton made a powerful plea Sunday for the rights of women in Afghanistan, using a global forum to insist that they must be part of the country's future growth.

"The United States believes strongly that no nation can achieve peace, stability and economic growth if half the population is not empowered," she told the Tokyo conference on Afghanistan.

Clinton said the way forward "must include fighting corruption, improving governance, strengthening the rule of law (and providing) access to economic opportunity for all Afghans, especially for women".

"All citizens need to have the chance to benefit from and contribute to Afghanistan's progress. The United States will continue to stand strongly by the women of Afghanistan."

Top diplomat Clinton was addressing a world conference aiming to chart a way forward for the nation after NATO combat troops withdraw in 2014.

The talks have already raised pledges of $16 billion in civilian aid for the conflict-torn nation over the next four years.

Representatives from more than 80 nations and international organisations gathering in the Japanese capital later adopted the "Tokyo Declaration", pledging support and cash for Kabul.

Clinton told the meeting that the administration of US President Barack Obama would be asking Congress to agree to keep American civilian assistance to Afghanistan at or near current levels until 2017.

"We need to put the commitments together in order to achieve a future that is worthy of the sacrifice of the Afghan people and many nations represented around this table," Clinton said.

Washington says significant progress has been made on women's rights since the US-led invasion of 2001 toppled the Taliban, with the number of girls attending schools soaring and more women gaining employment.

According to figures provided by the US State Department, out of the eight million students enrolled in schools today, nearly 40 percent are girls. That contrasts sharply with 2002 when there were only 900,000 children in schools, virtually none of them girls.

The US says there are now 175,000 teachers in Afghanistan, about a third of them women, thanks to $316 million spent on education initiatives.

US officials said Clinton had raised the issue of women's rights with Afghan President Hamid Karzai during her brief visit to Kabul on Saturday, warning that they were a litmus test for the country's progress.

Many fear the recent gains for women are now under threat as NATO troops leave and Kabul seeks peace with Islamist insurgents.

In March Karzai endorsed an edict by the country's highest Islamic authority which stated women were worth less than men and should avoid mixing with men.

There have also been a number of reported mysterious incidents of girl students being taken to hospitals across Afghanistan after falling ill from suspected gas attacks or water poisoning.

A senior US official told reporters there was a fear that women's rights may be at risk, and countries at the Tokyo conference wanted to ensure the final document "was as strong as possible on women's issues".

"I certainly think in areas where insurgents are, you see women's rights being rolled back," he said, asking to remain anonymous.

"We are trying to set a standard. And the standard is that as you go forward... women's rights remain one of the fundamental interests of all of the countries certainly represented here today."

He added that in the closing sessions of Sunday's meetings, Afghan ministers had said the message on women's rights "had been heard".