"They have blocked the harbour. We can see a big warship in front of the harbour," Gunilla Kleiverga, a gynaecologist, told AFP by phone from an apartment near the harbour of Smir, 40km east of Tangier.
"We're making an alternative plan. So we're asking journalists to come to the harbour at 1pm GMT [when the ship is due to arrive]," she said, without elaborating.
An AFP photographer said police were preventing journalists from reaching the harbour.
Women on Waves, the Dutch group organising the trip, is seeking to inform women about how to induce "safe legal medical abortions", offer the necessary medication and start a discussion on legalising the practice in Morocco. They have already set up a hotline.
Kleiverga said that, despite being illegal, around 700 abortion take place in Morocco every day, many of them exposing the women to dangerous and sometimes fatal treatment.
On Wednesday, the health ministry announced that the ship was not authorised to operate in Morocco and called on the relevant authorities to prevent the visit from taking place.
"The ministry … has never been informed of this event and has not authorised any non-resident party or doctor in Morocco to carry out this medical intervention," it said.
"The ministry calls on the relevant authorities to do what it is necessary to ensure that the law is applied," a statement added.
But Kleiverga insisted that the boat would not counsel or treat women in Morocco, hinting that it might transport women outside Morocco's maritime borders before doing so.
"We are only treating women in international waters. We're on a Dutch ship, where Dutch law applies. Of course we [will] adhere to Moroccan law, and we're not going to offer abortions in Morocco," she added.
In the past 11 years, a Women on Waves ship has visited Ireland, Poland, Portugal and Spain, sparking protests in each country from pro-life groups. This is its first trip to a Muslim country.
Ordinary Moroccans voiced strong opposition on Wednesday to the visit, which local youth group the Alternative Movement for Individual Liberties (Mali) has helped to organise.
"Moroccan law forbids abortion. Moroccan religious identity say it is forbidden and so does Islam. So the government cannot allow this ship to come to Morocco," lawyer Abdelmalik Zaza told Al-Tajdid, the newspaper of ruling Islamist party the PJD. – Sapa-AFP