Article 18, 24 and 98, UNCLOS plus SOLAS reg 33. says they must accept them.
The duty to rescue
There is a duty pursuant to international law for a ship to attempt the rescue of persons at danger at sea. This duty is based on a long-standing and strongly felt moral obligation among seafarers. This is stated, for example, in the
United Nations Convention of the Law of the Sea (UNCLOS) Article 98 the
International Convention for the Safety of Life at Sea (SOLAS), Regulation V-33. All states recognize this duty.
One implication of this rule is that a state cannot legally prohibit its vessels from rescuing persons at sea: states must accept that their vessels engage in rescue operations. In the
International Convention on Maritime Search and Rescue (SAR), coastal states undertake the role to coordinate the SAR in respect of persons in specified areas (Article 2.3). There is a duty to organize such services (
UNCLOS Article 98 and
SOLAS, Regulation V-7). There are no provisions in the SAR convention that the particular state in charge of a specific area can direct foreign vessels whether to assist or not.
Within the 12 nautical miles of territorial waters, the state has general jurisdiction on other grounds (including the right to direct vessels how to assist or not to assist), but this jurisdiction does not extend to ships in passage assisting other vessels (
UNCLOS Articles 17-18).