ADDIS ABABA, May 7 (Reuters) - Ethiopia accused Amnesty International of a smear campaign against it on Wednesday after the rights group said Ethiopian troops in Somalia had killed civilians by slitting their throats.

Thousands of Ethiopian soldiers are stationed in Somalia where they are helping the government fight Islamist-led insurgents, among them al Shabaab militants who are designated by Washington as a foreign terrorist organisation.

In its second report on abuses in Somalia in two weeks, Amnesty said on Tuesday that all parties to the conflict had committed abuses.

However, it said it had received an increase in reports of violations of Somalis by Ethiopian troops, with allegations of gang rape and civilians having their throats slit among the most common.

"This is an outright and deliberate lie, fed to Amnesty by groups affiliated to al Shabaab, groups that use the cover of human rights to promote their terrorist agenda," Ethiopia's Foreign Affairs Ministry said in a statement.

"It is deplorable that Amnesty International has lent itself to an obviously disgraceful smear campaign against the armed forces of Ethiopia, using highly emotive, even racist language."

The ministry accused Amnesty of ignoring widespread human rights abuses by the al Shabaab, including assassinations of political and religious leaders, desecration of dead bodies and the cutting of throats of Muslim clerics who oppose it.

Al Shabaab is the armed wing of a sharia courts movement that ruled most of southern Somalia for six months in 2006 before being ousted by allied Somali-Ethiopian forces.

Ethiopia said the timing of Amnesty report was designed to help al Shabaab "in the recruitment of terrorists by deliberately inciting hatred and animosity based on lies" and to derail talks due to start in Djibouti on Saturday.

The United Nations has brokered tentative peace talks due to begin on Saturday between 15 officials sent by Somalia's interim government and a similar number of delegates from the Eritrea-based Somali opposition.

Amnesty urged Ethiopia to read its report and study the allegations against its troops, rather than issue accusations.

"In light of the devastating testimony we received from ordinary Somalis who have been the victims of brutal attacks by all parties to the conflict, we expect the Ethiopian government to support a call for an international independent commission into the serious crimes being committed," a spokesperson said.

Last month Amnesty said Ethiopian troops killed 21 people in Mogadishu's Al Hidaaya mosque, adding that seven of the victims had their throats slit. Ethiopia rejected the report and said its forces had never been involved in such incidents. (Additional reporting and writing by Katie Nguyen in Nairobi; Editing by Daniel Wallis