The Tomb of Tetaki in Thebes (TT 15) was investigated by Lord Carnarvon in 1908. It belonged to one of the 18th Dynasty (New Kingdom) officials of Thebes who was alive during the reign of Ahmose (1550-1525 BCE). A photographic record was made at the time of the opening, but, as a result of thefts, Arthur Weigall, the then Chief Inspector, decided to close the tomb. Howard Carter, who had joined Carnarvon in 1909, helped to write up the tomb in Five Years' Explorations at Thebes: a Record of Work Done 1907-1911 (Oxford 1912).
The tomb was reopened in 1924 by Professor Percy Edward Newberry (who held the first chair of Egyptology at the University of Liverpool). A copy of the tomb paintings was made by N. de Garis Davies ("The Tomb of Tetaky at Thebes (No. 15)", The Journal of Egyptian Archaeology 11, 1/2  10-18 [JSTOR]).
Further archaeological work on the tomb was conducted by Daniel Polz during the 1990s.
In 2000 and 2003 the Louvre in Paris acquired four funerary reliefs. In today's announcement, Dr Zahi Hawass, Secretary General of Egypt's Supreme Council of Antiquities (SCA), claimed, "The Louvre Museum refused to return four archaeological reliefs to Egypt that were stolen during the 1980s from the tomb of the noble Tetaki" (Paul Schemm, "Egypt cuts ties with France's Louvre museum", AP October 7, 2009). It is claimed that the reliefs were cut out of the tomb during the 1980s.
The vendor of the reliefs has not been stated, and the due diligence processes conducted by the Louvre have not been disclosed. However Frederic Mitterrand, the Minister of Culture for France, stated that the pieces had been acquired in "good faith" ("acquis de bonne foi") [press release]. (On the use of the phrase see here.) A statement from the Ministry continued, "It wasn't until November 2008, after archaeologists rediscovered the tomb from which the frescoes appear to have come, that serious doubts emerged about the legality of their removal from Egyptian territory."
A panel will review the case and decide if the reliefs should be returned to Egypt. Mitterand's statement makes it clear that the reliefs would be returned under the 1970 UNESCO Convention on the Means of Prohibiting and Preventing the Illicit Import, Export and Transfer of Ownership of Cultural Property (see further). This is widely considered to be the benchmark date for considering recently surfaced archaeological material. In the meantime, the Louvre-sponsored excavation at Saqqara has been suspended. A lecture due to be delivered in Egypt by former Louvre curator, Christiane Ziegler, has been cancelled.
Hawass is taking an equally firm line with the St. Louis Art Museum over a mummy case excavated at Saqqara.
Egypt is also seeking the return of "historic" finds (i.e. material acquired prior to 1970) from western museums, among them the Rosetta Stone in London's British Museum (see comments and video of Hawass) and the head of Nefertiti in Berlin.
French authorities seem to be treating Egypt's claim seriously although it appears that the Louvre had refused earlier requests by Hawass.
UPDATE (October 9, 2009): Fragments to be returned to Egypt. Click here.