The Netherlands said Tuesday that it had requested China explain why police barred the daughter of disabled activist Ni Yulan from leaving Beijing to collect a rights award on her mother's behalf.

Dong Xuan told AFP she tried to leave Beijing last week but police grabbed her at the airport and stopped her from going to The Hague to accept the 100,000-euro ($131,000) Dutch government Human Rights Defenders Tulip award.

"Dong Xuan was supposed to receive the award on behalf of her mother, but did not... get permission of the Chinese authorities to leave China," Machtelt Schelling, spokeswoman for the Dutch embassy in Beijing, told AFP.

"Minister of Foreign Affairs (Uri) Rosenthal has requested an explanation from the Chinese authorities."

Dong, who is in her late 20s, said a policeman had been following her since her attempt to leave the country on January 25.

"He even tries to stop me from going out into the street to walk around. On Sunday the police came and searched my house," she said.

The Ministry of Public Security was not immediately available for comment.

Ni, 51, who has been confined to a wheelchair since 2002 when her knee caps and feet were broken in detention, and her husband Dong Jiqin have long helped victims of land grabs.

They were detained in April as authorities rounded up scores of activists amid anonymous online calls for protests similar to those that swept across the Arab world, and were tried in late December for "provoking trouble".

China is gearing up for a major 10-yearly leadership transition late this year and is clamping down on dissidents and strengthening security in volatile areas in an apparent bid to avoid unrest.

The Beijing court where the couple were tried has yet to reach a verdict and they remain behind bars.

Ni was awarded the Dutch government's prize "in recognition for her work on behalf of citizens of Beijing whose houses were confiscated and demolished in the run-up to the 2008 Olympic Games", organisers said on their website.

The award ceremony is due to take place Tuesday in The Hague.

Ni -- a trained lawyer -- has long been a thorn in the side of authority.

She was sentenced to a year in jail in 2002 for "obstructing official business" and for two years in 2008 for "harming public property" -- charges brought against her as she tried to protect her home from demolition.

Ni has a large following of supporters throughout China, many of whom have been evicted from their homes in government-backed land grabs -- one of the nation's most explosive social issues.

Her case has been championed by numerous Western governments, including the United States and the European Union, which sent representatives to meet her during a brief period of freedom in 2010.