* Court cases deadlocked by block on Kurdish defence
* Talks underway to end 28-year-old insurgency
* Kurdish MPs visit to Ocalan delayed by Erdogan spat
By Daren Butler
ISTANBUL, Jan 25 (Reuters) - Turkey's parliament passed a law late on Thursday allowing defendants to speak Kurdish in court, addressing a key demand of Kurdish politicians as Ankara seeks to advance peace talks with the jailed rebel leader of a 28-year-old insurgency.
Kurdish and nationalist deputies clashed verbally and nearly came to blows during a tense debate over a reform seen aimed at breaking a deadlock in trials of hundreds of people accused of links to the Kurdistan Workers Party (PKK) militant group.
Courts have rejected suspects' efforts to use Kurdish in defending against charges of membership in a PKK umbrella group. The new legislation will allow defendants to speak in their mother tongue, if they speak it better than they do Turkish.
The court defence reform was among the demands of hundreds of jailed PKK rebels who late last year staged a hunger strike which was ended by the intervention of their leader Abdullah Ocalan, in prison on the island of Imrali, south of Istanbul.
Ocalan's intervention is viewed as having paved the way for the government to launch peace talks with him, aimed at ending a conflict in which more than 40,000 people have been killed since his separatist guerrillas took up arms in 1984.
Intelligence agency officials have held talks with Ocalan, establishing a framework for a deal under which the PKK would stop fighting, withdraw from Turkish soil and disarm, according to media reports. In return, the government would carry out reforms boosting Kurdish minority rights.
Deputies from Prime Minister Tayyip Erdogan's ruling AK Party and the pro-Kurdish Peace and Democracy Party (BDP) voted in favour of the new law, while other opposition deputies voted against.
However, the BDP was critical of the law's requirement that defendants speaking their mother tongue pay for a translator.
Writing by Daren Butler; Editing by Jon Boyle