(Reuters) — Chad has recalled its ambassador to neighboring Cameroon in the latest escalation of a dispute over the sale by Exxon Mobil of its oil assets in both countries to Savannah Energy.

Chad said in a statement late on Thursday that the president of the landlocked Central African state decided to recall its ambassador due to "entrenched disagreements" over the sale.

Exxon closed the sale of its operations in Chad and Cameroon to Africa-focused oil and gas producer Savannah in a $407 million deal in December. But the Chadian government has challenged the agreement saying the final terms of the deal were different from what had been presented to it.

Chad has nationalized the assets on its side of the border, including Exxon's share of the over 1,000-km (621-mile) Chad-Cameroon oil pipeline.

Chad said in the statement on Thursday that it had reached out to Cameroon to raise concerns about "unfriendly actions" by some Cameroon officials that were contrary to the interests of Chad in the board of the pipeline company but did not get any response.

"Chad finds itself once again in the obligation to defend its interests and its respectability and denounces the repeated actions of Cameroon and its representatives which undermine, relations between the two countries," the statement said.

"Consequently, Chad has decided recall its ambassador to Cameroon for consultation," it added.

A Cameroon government spokesman, and the foreign ministry did not reply to requests for comments.

Savannah Energy has said it will pursue its legal rights over Chad's decision to nationalize Exxon's assets it had acquired.

The company said on Wednesday that it had sold a 10% stake of the share capital of the Cameroon Oil Transportation Company which owns and operates the 903km Cameroon section of the Chad-Cameroon pipeline to Cameroon national oil company (SNH).

According to the deal, Cameroon's SNH will pay a cash consideration of $44.9 million to Savannah Energy. Chad said in its statement that it was not informed of this sale which was contrary to the status of the pipeline company.