A Filipino-American woman seized more than two months ago in the southern Philippines has been released, officials on Basilan island say.Gerfa Yeatts Lunsmann was freed on Sunday evening and walked to a local township.Her American son Kevin, 14, and a Filipino nephew Romnick Jakaria, 19, seized with her, are still being held by suspected Abu Sayyaf militants.It is not known whether a ransom was paid to secure her release.Ms Lunsmann is \"a bit weak\" after her ordeal, said Zamboanga city Mayor Celso Lobregat.\"We thank God for this release,\" he added.The US embassy said in a statement that the release \"could not have occurred without the concerted efforts of Philippine government officials\" and the personal involvement of Mayor Lobregat.Ms Lunsmann was dropped off by boat at a wharf in an isolated area of Basilan island late on Sunday night, officials said.She was picked up by a police patrol as she walked towards the nearby Maluso township.Regional military spokesman Lt Col Randolph Cabangbang said she was taken to a military base in Zamboanga for health checks.Ms Lunsmann, a 41-year-old vet, was kidnapped with her son and nephew on 12 July while holidaying at a resort on the island of Tictabon, near Zamboanga.Shortly after their abduction, unnamed local officials said the kidnappers had demanded a huge ransom for their release.This was never confirmed, and no mention has since been made of whether a ransom had been paid.Kidnap-for-ransom groups are prevelant in the southern Philippines, the BBC\'s Kate McGeown in Manila reports.The Abu Sayyaf Islamic group is particularly well-known for using kidnapping as a way to raise funds, she adds.Ms Lunsmann was born near Zamboanga city but was adopted by a US family and grew up in the United States.She lives in Virginia, but has visited the southern Philippines province of Mindanao at least five times before, local police said.